(maint) code clean up (#187)

## bdfr

- Add the bound instance as method parameter
- Change methods not using its bound instance to staticmethods
- Fix dangerous default argument
- Refactor the comparison involving `not`
- Refactor unnecessary `else` / `elif` when `if` block has a `raise` statement
- Refactor unnecessary `else` / `elif` when `if` block has a `return` statement
- Refactor useless `else` block in the loop
- Remove implicit `object` from the base class
- Remove reimported module
- Remove unnecessary generator
- Remove unnecessary return statement
- Remove unnecessary use of comprehension
- Remove unused imports
- Use `is` to compare type of objects
- Using not x can cause unwanted results

## Dockerfile

- use a pinned Python version tag instead of latest
- leverage cached requirements

Signed-off-by: Vladislav Doster <mvdoster@gmail.com>

Co-authored-by: Ali Parlakçı <parlakciali@gmail.com>

src/downloaders/Erome.py

@@ -1,19 +1,18 @@
 import os
-import logging
-import sys
 import urllib.request
 from html.parser import HTMLParser
 
 from src.downloaders.downloaderUtils import getFile
 from src.downloaders.downloaderUtils import getExtension
 
-from src.errors import (FileNameTooLong, AlbumNotDownloadedCompletely, 
-                        NotADownloadableLinkError, FileAlreadyExistsError, full_exc_info)
+from src.errors import (AlbumNotDownloadedCompletely,
+                        NotADownloadableLinkError, FileAlreadyExistsError)
 from src.utils import GLOBAL
 from src.utils import printToFile as print
 
+
 class Erome:
-    def __init__(self,directory,post):
+    def __init__(self, directory, post):
         try:
             IMAGES = self.getLinks(post['CONTENTURL'])
         except urllib.error.HTTPError:
@@ -24,19 +23,20 @@ class Erome:
         duplicates = 0
 
         if imagesLenght == 1:
-            
+
             extension = getExtension(IMAGES[0])
 
             """Filenames are declared here"""
 
-            filename = GLOBAL.config['filename'].format(**post)+post["EXTENSION"]
+            filename = GLOBAL.config['filename'].format(
+                **post) + post["EXTENSION"]
             shortFilename = post['POSTID'] + extension
 
             imageURL = IMAGES[0]
             if 'https://' not in imageURL or 'http://' not in imageURL:
                 imageURL = "https://" + imageURL
 
-            getFile(filename,shortFilename,directory,imageURL)
+            getFile(filename, shortFilename, directory, imageURL)
 
         else:
             filename = GLOBAL.config['filename'].format(**post)
@@ -53,22 +53,22 @@ class Erome:
                 os.makedirs(folderDir)
 
             for i in range(imagesLenght):
-                
+
                 extension = getExtension(IMAGES[i])
 
-                filename = str(i+1)+extension
+                filename = str(i + 1) + extension
                 imageURL = IMAGES[i]
                 if 'https://' not in imageURL and 'http://' not in imageURL:
                     imageURL = "https://" + imageURL
 
-                print("  ({}/{})".format(i+1,imagesLenght))
+                print("  ({}/{})".format(i + 1, imagesLenght))
                 print("  {}".format(filename))
 
                 try:
-                    getFile(filename,filename,folderDir,imageURL,indent=2)
+                    getFile(filename, filename, folderDir, imageURL, indent=2)
                     print()
                 except FileAlreadyExistsError:
-                    print("  The file already exists" + " "*10,end="\n\n")
+                    print("  The file already exists" + " " * 10, end="\n\n")
                     duplicates += 1
                     howManyDownloaded -= 1
 
@@ -87,20 +87,21 @@ class Erome:
 
             if duplicates == imagesLenght:
                 raise FileAlreadyExistsError
-            elif howManyDownloaded + duplicates < imagesLenght:
+            if howManyDownloaded + duplicates < imagesLenght:
                 raise AlbumNotDownloadedCompletely(
                     "Album Not Downloaded Completely"
                 )
 
-    def getLinks(self,url,lineNumber=129):
- 
+    def getLinks(self, url, lineNumber=129):
+
         content = []
         lineNumber = None
 
         class EromeParser(HTMLParser):
             tag = None
+
             def handle_starttag(self, tag, attrs):
-                self.tag = {tag:{attr[0]: attr[1] for attr in attrs}}
+                self.tag = {tag: {attr[0]: attr[1] for attr in attrs}}
 
         pageSource = (urllib.request.urlopen(url).read().decode().split('\n'))
 
@@ -109,7 +110,7 @@ class Erome:
             obj = EromeParser()
             obj.feed(pageSource[i])
             tag = obj.tag
-            
+
             if tag is not None:
                 if "div" in tag:
                     if "id" in tag["div"]:
@@ -124,12 +125,12 @@ class Erome:
             if tag is not None:
                 if "img" in tag:
                     if "class" in tag["img"]:
-                        if tag["img"]["class"]=="img-front":
+                        if tag["img"]["class"] == "img-front":
                             content.append(tag["img"]["src"])
                 elif "source" in tag:
                     content.append(tag["source"]["src"])
-                    
+
         return [
-            link for link in content \
+            link for link in content
             if link.endswith("_480p.mp4") or not link.endswith(".mp4")
-        ]
+        ]