diff --git a/Pipfile b/Pipfile
index 9524d0e..3abb1aa 100644
--- a/Pipfile
+++ b/Pipfile
@@ -13,3 +13,4 @@ sphinx-rtd-theme = "*"
 radon = "*"
 "flake8" = "*"
 httpretty = "*"
+pylint = "*"
diff --git a/Pipfile.lock b/Pipfile.lock
index a0b3690..e886064 100644
--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "01fabf42a826553591227799f7bee2447edf81a6bec93559917576e2b1018c8d"
+            "sha256": "2fdcfcd032fa6e2b1aef868df499755a8a4e1038c2c08d6fbc6ee9cd777d05b8"
         },
         "pipfile-spec": 6,
         "requires": {},
@@ -35,9 +35,10 @@
         },
         "cfscrape": {
             "hashes": [
-                "sha256:cb9159955d0e6e82cf4ad8cc9b19413e68ebfed1ce98a26e51f62e66d45146f1"
+                "sha256:0794aa78e586a3af578ff0869f95779bd1702adcdbc9369e8dc470435caaf020",
+                "sha256:fa7fc172e6872f461377216ddd5a6d82c9650b9d10cac5aa0239998daf3e093a"
             ],
-            "version": "==1.9.5"
+            "version": "==1.9.7"
         },
         "chardet": {
             "hashes": [
@@ -90,17 +91,17 @@
         },
         "requests-cache": {
             "hashes": [
-                "sha256:e9270030becc739b0a7f7f834234c73a878b2d794122bf76f40055a22419eb67",
-                "sha256:fe561ca119879bbcfb51f03a35e35b425e18f338248e59fd5cf2166c77f457a2"
+                "sha256:6822f788c5ee248995c4bfbd725de2002ad710182ba26a666e85b64981866060",
+                "sha256:73a7211870f7d67af5fd81cad2f67cfe1cd3eb4ee6a85155e07613968cc72dfc"
             ],
-            "version": "==0.4.13"
+            "version": "==0.5.0"
         },
         "soupsieve": {
             "hashes": [
-                "sha256:afa56bf14907bb09403e5d15fbed6275caa4174d36b975226e3b67a3bb6e2c4b",
-                "sha256:eaed742b48b1f3e2d45ba6f79401b2ed5dc33b2123dfe216adb90d4bfa0ade26"
+                "sha256:6898e82ecb03772a0d82bd0d0a10c0d6dcc342f77e0701d0ec4a8271be465ece",
+                "sha256:b20eff5e564529711544066d7dc0f7661df41232ae263619dede5059799cdfca"
             ],
-            "version": "==1.8"
+            "version": "==1.9.1"
         },
         "tabulate": {
             "hashes": [
@@ -110,10 +111,10 @@
         },
         "urllib3": {
             "hashes": [
-                "sha256:61bf29cada3fc2fbefad4fdf059ea4bd1b4a86d2b6d15e1c7c0b582b9752fe39",
-                "sha256:de9529817c93f27c8ccbfead6985011db27bd0ddfcdb2d86f3f663385c6a9c22"
+                "sha256:4c291ca23bbb55c76518905869ef34bdd5f0e46af7afe6861e8375643ffee1a0",
+                "sha256:9a247273df709c4fedb38c711e44292304f73f39ab01beda9f6b9fc375669ac3"
             ],
-            "version": "==1.24.1"
+            "version": "==1.24.2"
         }
     },
     "develop": {
@@ -124,6 +125,13 @@
             ],
             "version": "==0.7.12"
         },
+        "astroid": {
+            "hashes": [
+                "sha256:6560e1e1749f68c64a4b5dee4e091fce798d2f0d84ebe638cf0e0585a343acf4",
+                "sha256:b65db1bbaac9f9f4d190199bb8680af6f6f84fd3769a5ea883df8a91fe68b4c4"
+            ],
+            "version": "==2.2.5"
+        },
         "babel": {
             "hashes": [
                 "sha256:6778d85147d5d85345c14a26aada5e478ab04e39b078b0745ee6870c2b5cf669",
@@ -210,12 +218,53 @@
             ],
             "version": "==1.1.0"
         },
+        "isort": {
+            "hashes": [
+                "sha256:01cb7e1ca5e6c5b3f235f0385057f70558b70d2f00320208825fa62887292f43",
+                "sha256:268067462aed7eb2a1e237fcb287852f22077de3fb07964e87e00f829eea2d1a"
+            ],
+            "version": "==4.3.17"
+        },
         "jinja2": {
             "hashes": [
-                "sha256:74c935a1b8bb9a3947c50a54766a969d4846290e1e788ea44c1392163723c3bd",
-                "sha256:f84be1bb0040caca4cea721fcbbbbd61f9be9464ca236387158b0feea01914a4"
+                "sha256:065c4f02ebe7f7cf559e49ee5a95fb800a9e4528727aec6f24402a5374c65013",
+                "sha256:14dd6caf1527abb21f08f86c784eac40853ba93edb79552aa1e4b8aef1b61c7b"
             ],
-            "version": "==2.10"
+            "version": "==2.10.1"
+        },
+        "lazy-object-proxy": {
+            "hashes": [
+                "sha256:0ce34342b419bd8f018e6666bfef729aec3edf62345a53b537a4dcc115746a33",
+                "sha256:1b668120716eb7ee21d8a38815e5eb3bb8211117d9a90b0f8e21722c0758cc39",
+                "sha256:209615b0fe4624d79e50220ce3310ca1a9445fd8e6d3572a896e7f9146bbf019",
+                "sha256:27bf62cb2b1a2068d443ff7097ee33393f8483b570b475db8ebf7e1cba64f088",
+                "sha256:27ea6fd1c02dcc78172a82fc37fcc0992a94e4cecf53cb6d73f11749825bd98b",
+                "sha256:2c1b21b44ac9beb0fc848d3993924147ba45c4ebc24be19825e57aabbe74a99e",
+                "sha256:2df72ab12046a3496a92476020a1a0abf78b2a7db9ff4dc2036b8dd980203ae6",
+                "sha256:320ffd3de9699d3892048baee45ebfbbf9388a7d65d832d7e580243ade426d2b",
+                "sha256:50e3b9a464d5d08cc5227413db0d1c4707b6172e4d4d915c1c70e4de0bbff1f5",
+                "sha256:5276db7ff62bb7b52f77f1f51ed58850e315154249aceb42e7f4c611f0f847ff",
+                "sha256:61a6cf00dcb1a7f0c773ed4acc509cb636af2d6337a08f362413c76b2b47a8dd",
+                "sha256:6ae6c4cb59f199d8827c5a07546b2ab7e85d262acaccaacd49b62f53f7c456f7",
+                "sha256:7661d401d60d8bf15bb5da39e4dd72f5d764c5aff5a86ef52a042506e3e970ff",
+                "sha256:7bd527f36a605c914efca5d3d014170b2cb184723e423d26b1fb2fd9108e264d",
+                "sha256:7cb54db3535c8686ea12e9535eb087d32421184eacc6939ef15ef50f83a5e7e2",
+                "sha256:7f3a2d740291f7f2c111d86a1c4851b70fb000a6c8883a59660d95ad57b9df35",
+                "sha256:81304b7d8e9c824d058087dcb89144842c8e0dea6d281c031f59f0acf66963d4",
+                "sha256:933947e8b4fbe617a51528b09851685138b49d511af0b6c0da2539115d6d4514",
+                "sha256:94223d7f060301b3a8c09c9b3bc3294b56b2188e7d8179c762a1cda72c979252",
+                "sha256:ab3ca49afcb47058393b0122428358d2fbe0408cf99f1b58b295cfeb4ed39109",
+                "sha256:bd6292f565ca46dee4e737ebcc20742e3b5be2b01556dafe169f6c65d088875f",
+                "sha256:cb924aa3e4a3fb644d0c463cad5bc2572649a6a3f68a7f8e4fbe44aaa6d77e4c",
+                "sha256:d0fc7a286feac9077ec52a927fc9fe8fe2fabab95426722be4c953c9a8bede92",
+                "sha256:ddc34786490a6e4ec0a855d401034cbd1242ef186c20d79d2166d6a4bd449577",
+                "sha256:e34b155e36fa9da7e1b7c738ed7767fc9491a62ec6af70fe9da4a057759edc2d",
+                "sha256:e5b9e8f6bda48460b7b143c3821b21b452cb3a835e6bbd5dd33aa0c8d3f5137d",
+                "sha256:e81ebf6c5ee9684be8f2c87563880f93eedd56dd2b6146d8a725b50b7e5adb0f",
+                "sha256:eb91be369f945f10d3a49f5f9be8b3d0b93a4c2be8f8a5b83b0571b8123e0a7a",
+                "sha256:f460d1ceb0e4a5dcb2a652db0904224f367c9b3c1470d5a7683c0480e582468b"
+            ],
+            "version": "==1.3.1"
         },
         "mando": {
             "hashes": [
@@ -299,19 +348,27 @@
             ],
             "version": "==2.3.1"
         },
+        "pylint": {
+            "hashes": [
+                "sha256:5d77031694a5fb97ea95e828c8d10fc770a1df6eb3906067aaed42201a8a6a09",
+                "sha256:723e3db49555abaf9bf79dc474c6b9e2935ad82230b10c1138a71ea41ac0fff1"
+            ],
+            "index": "pypi",
+            "version": "==2.3.1"
+        },
         "pyparsing": {
             "hashes": [
-                "sha256:66c9268862641abcac4a96ba74506e594c884e3f57690a696d21ad8210ed667a",
-                "sha256:f6c5ef0d7480ad048c054c37632c67fca55299990fff127850181659eea33fc3"
+                "sha256:1873c03321fc118f4e9746baf201ff990ceb915f433f23b395f5580d1840cb2a",
+                "sha256:9b6323ef4ab914af344ba97510e966d64ba91055d6b9afa6b30799340e89cc03"
             ],
-            "version": "==2.3.1"
+            "version": "==2.4.0"
         },
         "pytz": {
             "hashes": [
-                "sha256:32b0891edff07e28efe91284ed9c31e123d84bea3fd98e1f72be2508f43ef8d9",
-                "sha256:d5f05e487007e29e03409f9398d074e158d920d36eb82eaf66fb1136b0c5374c"
+                "sha256:303879e36b721603cc54604edcac9d20401bdbe31e1e4fdee5b9f98d5d31dfda",
+                "sha256:d747dd3d23d77ef44c6a3526e274af6efeb0a6f1afd5a69ba4d5be4098c8e141"
             ],
-            "version": "==2018.9"
+            "version": "==2019.1"
         },
         "radon": {
             "hashes": [
@@ -358,11 +415,11 @@
         },
         "sphinx": {
             "hashes": [
-                "sha256:9f3e17c64b34afc653d7c5ec95766e03043cc6d80b0de224f59b6b6e19d37c3c",
-                "sha256:c7658aab75c920288a8cf6f09f244c6cfdae30d82d803ac1634d9f223a80ca08"
+                "sha256:423280646fb37944dd3c85c58fb92a20d745793a9f6c511f59da82fa97cd404b",
+                "sha256:de930f42600a4fef993587633984cc5027dedba2464bcf00ddace26b40f8d9ce"
             ],
             "index": "pypi",
-            "version": "==1.8.5"
+            "version": "==2.0.1"
         },
         "sphinx-rtd-theme": {
             "hashes": [
@@ -372,12 +429,47 @@
             "index": "pypi",
             "version": "==0.4.3"
         },
-        "sphinxcontrib-websupport": {
+        "sphinxcontrib-applehelp": {
             "hashes": [
-                "sha256:68ca7ff70785cbe1e7bccc71a48b5b6d965d79ca50629606c7861a21b206d9dd",
-                "sha256:9de47f375baf1ea07cdb3436ff39d7a9c76042c10a769c52353ec46e4e8fc3b9"
+                "sha256:edaa0ab2b2bc74403149cb0209d6775c96de797dfd5b5e2a71981309efab3897",
+                "sha256:fb8dee85af95e5c30c91f10e7eb3c8967308518e0f7488a2828ef7bc191d0d5d"
             ],
-            "version": "==1.1.0"
+            "version": "==1.0.1"
+        },
+        "sphinxcontrib-devhelp": {
+            "hashes": [
+                "sha256:6c64b077937330a9128a4da74586e8c2130262f014689b4b89e2d08ee7294a34",
+                "sha256:9512ecb00a2b0821a146736b39f7aeb90759834b07e81e8cc23a9c70bacb9981"
+            ],
+            "version": "==1.0.1"
+        },
+        "sphinxcontrib-htmlhelp": {
+            "hashes": [
+                "sha256:4670f99f8951bd78cd4ad2ab962f798f5618b17675c35c5ac3b2132a14ea8422",
+                "sha256:d4fd39a65a625c9df86d7fa8a2d9f3cd8299a3a4b15db63b50aac9e161d8eff7"
+            ],
+            "version": "==1.0.2"
+        },
+        "sphinxcontrib-jsmath": {
+            "hashes": [
+                "sha256:2ec2eaebfb78f3f2078e73666b1415417a116cc848b72e5172e596c871103178",
+                "sha256:a9925e4a4587247ed2191a22df5f6970656cb8ca2bd6284309578f2153e0c4b8"
+            ],
+            "version": "==1.0.1"
+        },
+        "sphinxcontrib-qthelp": {
+            "hashes": [
+                "sha256:513049b93031beb1f57d4daea74068a4feb77aa5630f856fcff2e50de14e9a20",
+                "sha256:79465ce11ae5694ff165becda529a600c754f4bc459778778c7017374d4d406f"
+            ],
+            "version": "==1.0.2"
+        },
+        "sphinxcontrib-serializinghtml": {
+            "hashes": [
+                "sha256:c0efb33f8052c04fd7a26c0a07f1678e8512e0faec19f4aa8f2473a8b81d5227",
+                "sha256:db6615af393650bf1151a6cd39120c29abaf93cc60db8c48eb2dddbfdc3a9768"
+            ],
+            "version": "==1.1.3"
         },
         "tqdm": {
             "hashes": [
@@ -394,12 +486,38 @@
             "index": "pypi",
             "version": "==1.13.0"
         },
+        "typed-ast": {
+            "hashes": [
+                "sha256:04894d268ba6eab7e093d43107869ad49e7b5ef40d1a94243ea49b352061b200",
+                "sha256:16616ece19daddc586e499a3d2f560302c11f122b9c692bc216e821ae32aa0d0",
+                "sha256:252fdae740964b2d3cdfb3f84dcb4d6247a48a6abe2579e8029ab3be3cdc026c",
+                "sha256:2af80a373af123d0b9f44941a46df67ef0ff7a60f95872412a145f4500a7fc99",
+                "sha256:2c88d0a913229a06282b285f42a31e063c3bf9071ff65c5ea4c12acb6977c6a7",
+                "sha256:2ea99c029ebd4b5a308d915cc7fb95b8e1201d60b065450d5d26deb65d3f2bc1",
+                "sha256:3d2e3ab175fc097d2a51c7a0d3fda442f35ebcc93bb1d7bd9b95ad893e44c04d",
+                "sha256:4766dd695548a15ee766927bf883fb90c6ac8321be5a60c141f18628fb7f8da8",
+                "sha256:56b6978798502ef66625a2e0f80cf923da64e328da8bbe16c1ff928c70c873de",
+                "sha256:5cddb6f8bce14325b2863f9d5ac5c51e07b71b462361fd815d1d7706d3a9d682",
+                "sha256:644ee788222d81555af543b70a1098f2025db38eaa99226f3a75a6854924d4db",
+                "sha256:64cf762049fc4775efe6b27161467e76d0ba145862802a65eefc8879086fc6f8",
+                "sha256:68c362848d9fb71d3c3e5f43c09974a0ae319144634e7a47db62f0f2a54a7fa7",
+                "sha256:6c1f3c6f6635e611d58e467bf4371883568f0de9ccc4606f17048142dec14a1f",
+                "sha256:b213d4a02eec4ddf622f4d2fbc539f062af3788d1f332f028a2e19c42da53f15",
+                "sha256:bb27d4e7805a7de0e35bd0cb1411bc85f807968b2b0539597a49a23b00a622ae",
+                "sha256:c9d414512eaa417aadae7758bc118868cd2396b0e6138c1dd4fda96679c079d3",
+                "sha256:f0937165d1e25477b01081c4763d2d9cdc3b18af69cb259dd4f640c9b900fe5e",
+                "sha256:fb96a6e2c11059ecf84e6741a319f93f683e440e341d4489c9b161eca251cf2a",
+                "sha256:fc71d2d6ae56a091a8d94f33ec9d0f2001d1cb1db423d8b4355debfe9ce689b7"
+            ],
+            "markers": "implementation_name == 'cpython'",
+            "version": "==1.3.4"
+        },
         "urllib3": {
             "hashes": [
-                "sha256:61bf29cada3fc2fbefad4fdf059ea4bd1b4a86d2b6d15e1c7c0b582b9752fe39",
-                "sha256:de9529817c93f27c8ccbfead6985011db27bd0ddfcdb2d86f3f663385c6a9c22"
+                "sha256:4c291ca23bbb55c76518905869ef34bdd5f0e46af7afe6861e8375643ffee1a0",
+                "sha256:9a247273df709c4fedb38c711e44292304f73f39ab01beda9f6b9fc375669ac3"
             ],
-            "version": "==1.24.1"
+            "version": "==1.24.2"
         },
         "webencodings": {
             "hashes": [
@@ -407,6 +525,12 @@
                 "sha256:b36a1c245f2d304965eb4e0a82848379241dc04b865afcc4aab16748587e1923"
             ],
             "version": "==0.5.1"
+        },
+        "wrapt": {
+            "hashes": [
+                "sha256:4aea003270831cceb8a90ff27c4031da6ead7ec1886023b80ce0dfe0adf61533"
+            ],
+            "version": "==1.11.1"
         }
     }
 }
diff --git a/anime_downloader/.#util.py b/anime_downloader/.#util.py
new file mode 120000
index 0000000..ba58f0c
--- /dev/null
+++ b/anime_downloader/.#util.py
@@ -0,0 +1 @@
+vn-ki@this.1316:1557033979
\ No newline at end of file
diff --git a/anime_downloader/downloader/__init__.py b/anime_downloader/downloader/__init__.py
index 913ad25..4a2ec41 100644
--- a/anime_downloader/downloader/__init__.py
+++ b/anime_downloader/downloader/__init__.py
@@ -1,5 +1,12 @@
 from anime_downloader.downloader.http_downloader import HTTPDownloader
+from anime_downloader.downloader.external_downloader import ExternalDownloader
 
 
 def get_downloader(downloader):
-    return HTTPDownloader
+    """get_downloader returns the proper downloader class
+
+    TODO: Lazy loading of downloaders
+    """
+    if downloader == 'http':
+        return HTTPDownloader
+    return ExternalDownloader
diff --git a/anime_downloader/downloader/base_downloader.py b/anime_downloader/downloader/base_downloader.py
index 779cbf7..ba858c3 100644
--- a/anime_downloader/downloader/base_downloader.py
+++ b/anime_downloader/downloader/base_downloader.py
@@ -10,13 +10,16 @@ logger = logging.getLogger(__name__)
 
 
 class BaseDownloader:
-    def __init__(self, source, path, force, range_size=None):
+    def __init__(self, source, path, force, options=None):
         logger.info(path)
 
         self.url = source.stream_url
         self.referer = source.referer
         self.path = path
-        self.range_size = range_size
+
+        if options is None:
+            options = {}
+        self.options = options
 
         util.make_dir(path.rsplit('/', 1)[0])
 
diff --git a/anime_downloader/downloader/external_downloader.py b/anime_downloader/downloader/external_downloader.py
new file mode 100644
index 0000000..2964691
--- /dev/null
+++ b/anime_downloader/downloader/external_downloader.py
@@ -0,0 +1,34 @@
+from anime_downloader.downloader.base_downloader import BaseDownloader
+from anime_downloader import session
+
+from pathlib import Path
+import time
+import sys
+import subprocess
+
+session = session.get_session()
+
+
+class ExternalDownloader(BaseDownloader):
+    def _download(self):
+        executable = self.options['executable']
+        opts = self.options['cmd_opts']
+        path = Path(self.path)
+
+        # TODO: Pull this into downloadersession?
+        rep_dict = {
+            'stream_url': self.url,
+            'file_format': str(path.name),
+            'download_dir': str(path.parent.absolute()),
+            'referer': self.referer,
+        }
+
+        cmd = [executable] + opts
+        cmd = [c.format(**rep_dict) for c in cmd]
+        p = subprocess.Popen(cmd)
+        return_code = p.wait()
+
+        if return_code != 0:
+            # Sleep for a while to make sure downloader exits correctly
+            time.sleep(2)
+            sys.exit(1)
diff --git a/anime_downloader/downloader/http_downloader.py b/anime_downloader/downloader/http_downloader.py
index 14393e0..bc6b26a 100644
--- a/anime_downloader/downloader/http_downloader.py
+++ b/anime_downloader/downloader/http_downloader.py
@@ -8,13 +8,13 @@ session = session.get_session()
 
 class HTTPDownloader(BaseDownloader):
     def _download(self):
-        if self.range_size is None:
+        if self.options['range_size'] is None:
             self._non_range_download()
         else:
             self._ranged_download()
 
     def _ranged_download(self):
-        http_chunksize = self.range_size
+        http_chunksize = self.options['range_size']
 
         range_start = 0
         range_end = http_chunksize
diff --git a/anime_downloader/session.py b/anime_downloader/session.py
index f36caec..63679f1 100644
--- a/anime_downloader/session.py
+++ b/anime_downloader/session.py
@@ -1,14 +1,18 @@
+import logging
+
 import requests
+import requests_cache
 import urllib3
 from requests.adapters import HTTPAdapter
 from requests.packages.urllib3.util.retry import Retry
-import requests_cache
+import tempfile
 
-import logging
+from anime_downloader import downloader
 
 logger = logging.getLogger(__name__)
 
-requests_cache.install_cache('anime_downloader', expires_after=300)
+file = tempfile.mktemp()
+requests_cache.install_cache('anime_downloader', expires_after=300, location=file)
 
 _session = requests_cache.CachedSession()
 
@@ -45,3 +49,32 @@ def get_session(custom_session=None):
     _session.hooks = {'response': hook}
 
     return _session
+
+
+class DownloaderSession:
+    external_downloaders = {
+        "aria2": {
+            "executable": "aria2c",
+            "cmd_opts": [
+                "{stream_url}", "-x", "12", "-s", "12",
+                "-j", "12", "-k", "10M", "-o", "{file_format}",
+                "--continue", "true", "--dir", "{download_dir}",
+                "--stream-piece-selector", "inorder", "--min-split-size",
+                "5M", "--referer", "{referer}"
+            ],
+            "_disable_ssl_additional": ["--check-certificate", "false"],
+        },
+    }
+
+    def __init__(self, disable_ssl=False):
+        # TODO: Figure out a way to do disable_ssl elgantly
+        # Disablining ssl check should be in session and not in
+        # donwloader because it's a session wise option
+
+        # TODO: Add ability to add downloaders using config
+        pass
+
+    def __getitem__(self, key):
+        if key == 'http':
+            return downloader.get_downloader('http')()
+        return self.down
diff --git a/anime_downloader/sites/anime.py b/anime_downloader/sites/anime.py
index 2793e2d..6ed7816 100644
--- a/anime_downloader/sites/anime.py
+++ b/anime_downloader/sites/anime.py
@@ -42,7 +42,7 @@ class Anime:
     title = ''
     meta = dict()
     subclasses = {}
-    QUALITIES = None
+    QUALITIES = []
 
     @classmethod
     def search(cls, query):
@@ -62,9 +62,13 @@ class Anime:
         return
 
     def __init__(self, url=None, quality='720p',
-                 fallback_qualities=['720p', '480p', '360p'],
+                 fallback_qualities=None,
                  _skip_online_data=False):
         self.url = url
+
+        if fallback_qualities is None:
+            fallback_qualities = ['720p', '480p', '360p']
+
         self._fallback_qualities = [
             q for q in fallback_qualities if q in self.QUALITIES]
 
@@ -80,8 +84,8 @@ class Anime:
             self._len = len(self._episode_urls)
 
     @classmethod
-    def verify_url(self, url):
-        if self.sitename in url:
+    def verify_url(cls, url):
+        if cls.sitename in url:
             return True
         return False
 
@@ -91,6 +95,19 @@ class Anime:
 
     @classmethod
     def factory(cls, sitename: str):
+        """
+        factory returns the appropriate subclass for the given site name.
+
+        Parameters
+        ----------
+        sitename: str
+            sitename is the name of the site
+
+        Returns
+        -------
+        subclass of :py:class:`Anime`
+            Sub class of :py:class:`Anime`
+        """
         return cls.subclasses[sitename]
 
     @classmethod
@@ -155,12 +172,13 @@ class Anime:
         episode_class = AnimeEpisode.subclasses[self.sitename]
         if isinstance(index, int):
             ep_id = self._episode_urls[index]
-            return episode_class(ep_id[1], self.quality, parent=self,
+            return episode_class(ep_id[1], parent=self,
                                  ep_no=ep_id[0])
         elif isinstance(index, slice):
             anime = copy.deepcopy(self)
             anime._episode_urls = anime._episode_urls[index]
             return anime
+        return None
 
     def __repr__(self):
         return '''
@@ -175,7 +193,7 @@ Episode count: {length}
     def __str__(self):
         return self.title
 
-    def _scarpe_episodes(self, soup):
+    def _scarpe_episodes(self):
         """
         _scarpe_episodes is function which has to be overridden by the base
         classes to scrape the episode urls from the web page.
@@ -193,7 +211,7 @@ Episode count: {length}
         """
         return
 
-    def _scrape_metadata(self, soup):
+    def _scrape_metadata(self):
         """
         _scrape_metadata is function which has to be overridden by the base
         classes to scrape the metadata of anime from the web page.
@@ -208,19 +226,40 @@ Episode count: {length}
 
 
 class AnimeEpisode:
-    QUALITIES = None
+    """
+    Base class for all Episode classes.
+
+    Parameters
+    ----------
+    url: string
+        URL of the episode.
+    quality: One of ['360p', '480p', '720p', '1080p']
+        Quality of episode
+    fallback_qualities: list
+        The order of fallback.
+
+    Attributes
+    ----------
+    sitename: str
+        name of the site
+    title: str
+        Title of the anime
+    meta: dict
+        metadata about the anime. [Can be empty]
+    QUALITIES: list
+        Possible qualities for the site
+    """
+    QUALITIES = []
     title = ''
     stream_url = ''
     subclasses = {}
 
-    def __init__(self, url, quality='720p', parent=None,
-                 ep_no=None):
-        if quality not in self.QUALITIES:
-            raise AnimeDLError('Incorrect quality: "{}"'.format(quality))
+    def __init__(self, url, parent: Anime = None, ep_no=None):
 
         self.ep_no = ep_no
         self.url = url
-        self.quality = quality
+        self.quality = parent.quality
+        self.QUALITIES = parent.QUALITIES
         self._parent = parent
         self._sources = None
         self.pretty_title = '{}-{}'.format(self._parent.title, self.ep_no)
diff --git a/anime_downloader/sites/kissanime.py b/anime_downloader/sites/kissanime.py
index c5ad3cd..6bb10d4 100644
--- a/anime_downloader/sites/kissanime.py
+++ b/anime_downloader/sites/kissanime.py
@@ -9,6 +9,7 @@ logger = logging.getLogger(__name__)
 
 
 class KissanimeEpisode(AnimeEpisode, sitename='kissanime'):
+    """KissanimeEpisode"""
     QUALITIES = ['360p', '480p', '720p', '1080p']
     _base_url = 'http://kissanime.ru'
     VERIFY_HUMAN = True
@@ -25,6 +26,7 @@ class KissanimeEpisode(AnimeEpisode, sitename='kissanime'):
 
 
 class KissAnime(Anime, sitename='kissanime'):
+    """KissAnime"""
     sitename = 'kissanime'
     _referer = 'http://kissanime.ru'
     QUALITIES = ['360p', '480p', '720p', '1080p']
diff --git a/anime_downloader/sites/twistmoe.py b/anime_downloader/sites/twistmoe.py
index 2fc80cd..c939f22 100644
--- a/anime_downloader/sites/twistmoe.py
+++ b/anime_downloader/sites/twistmoe.py
@@ -1,7 +1,6 @@
 from Crypto.Cipher import AES
 import base64
 from hashlib import md5
-from bs4 import BeautifulSoup
 import warnings
 
 from anime_downloader import session
@@ -27,6 +26,7 @@ class TwistMoeEpisode(AnimeEpisode, sitename='twist.moe'):
 
 
 class TwistMoe(Anime, sitename='twist.moe'):
+    sitename = 'twist.moe'
     QUALITIES = ['360p', '480p', '720p', '1080p']
     _api_url = "https://twist.moe/api/anime/{}/sources"
 
diff --git a/anime_downloader/util.py b/anime_downloader/util.py
index d3af4d9..2d44d77 100644
--- a/anime_downloader/util.py
+++ b/anime_downloader/util.py
@@ -193,7 +193,7 @@ def format_command(cmd, episode, file_format, path):
     cmd_dict = {
         '{aria2}': 'aria2c {stream_url} -x 12 -s 12 -j 12 -k 10M -o '
                    '{file_format}.mp4 --continue=true --dir={download_dir}'
-                   ' --stream-piece-selector=inorder --min-split-size=5M --referer={referer}'
+                   ' --stream-piece-selector=inorder --min-split-size=5M --referer={referer} --check-certificate=false'
     }
     rep_dict = {
         'stream_url': episode.source().stream_url,