(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/jsonHelper.py

@@ -3,6 +3,7 @@ from os import path, remove
 
 from src.errors import InvalidJSONFile
 
+
 class JsonFile:
     """ Write and read JSON files
 
@@ -10,13 +11,13 @@ class JsonFile:
 
     Use delete(self,*deletedKeys) to delete keys
     """
-    
+
     FILEDIR = ""
 
-    def __init__(self,FILEDIR):
+    def __init__(self, FILEDIR):
         self.FILEDIR = FILEDIR
         if not path.exists(self.FILEDIR):
-            self.__writeToFile({},create=True)
+            self.__writeToFile({}, create=True)
 
     def read(self):
         try:
@@ -25,19 +26,21 @@ class JsonFile:
         except json.decoder.JSONDecodeError:
             raise InvalidJSONFile(f"{self.FILEDIR} cannot be read")
 
-    def add(self,toBeAdded,sub=None):
+    def add(self, toBeAdded, sub=None):
         """Takes a dictionary and merges it with json file.
         It uses new key's value if a key already exists.
         Returns the new content as a dictionary.
         """
 
         data = self.read()
-        if sub: data[sub] = {**data[sub], **toBeAdded}
-        else: data = {**data, **toBeAdded}
+        if sub:
+            data[sub] = {**data[sub], **toBeAdded}
+        else:
+            data = {**data, **toBeAdded}
         self.__writeToFile(data)
         return self.read()
 
-    def delete(self,*deleteKeys):
+    def delete(self, *deleteKeys):
         """Delete given keys from JSON file.
         Returns the new content as a dictionary.
         """
@@ -51,8 +54,8 @@ class JsonFile:
             return False
         self.__writeToFile(data)
 
-    def __writeToFile(self,content,create=False):
+    def __writeToFile(self, content, create=False):
         if not create:
             remove(self.FILEDIR)
         with open(self.FILEDIR, 'w') as f:
-            json.dump(content, f, indent=4)
+            json.dump(content, f, indent=4)