diff --git a/python3/vimspector/breakpoints.py b/python3/vimspector/breakpoints.py
index e15a649..0cc1d06 100644
--- a/python3/vimspector/breakpoints.py
+++ b/python3/vimspector/breakpoints.py
@@ -100,7 +100,7 @@ class ProjectBreakpoints( object ):
       return
 
     found_bp = False
-    for index, bp in enumerate( self._line_breakpoints[ file_name]  ):
+    for index, bp in enumerate( self._line_breakpoints[ file_name ] ):
       if bp[ 'line' ] == line:
         found_bp = True
         if bp[ 'state' ] == 'ENABLED':
@@ -151,7 +151,7 @@ class ProjectBreakpoints( object ):
   def SendBreakpoints( self ):
     if not self._breakpoints_handler:
       def handler( source, msg ):
-          return self._ShowBreakpoints()
+        return self._ShowBreakpoints()
     else:
       handler = self._breakpoints_handler
 
diff --git a/python3/vimspector/code.py b/python3/vimspector/code.py
index 9aa85da..e38f840 100644
--- a/python3/vimspector/code.py
+++ b/python3/vimspector/code.py
@@ -21,7 +21,7 @@ from collections import defaultdict
 from vimspector import utils
 
 
-class CodeView( object  ):
+class CodeView( object ):
   def __init__( self, window ):
     self._window = window
 
@@ -78,9 +78,9 @@ class CodeView( object  ):
     vim.command( 'sign place {0} group=VimspectorCode priority=20 '
                                  'line={1} name=vimspectorPC '
                                  'file={2}'.format(
-      self._signs[ 'vimspectorPC' ],
-      frame[ 'line' ],
-      frame[ 'source' ][ 'path' ] ) )
+                                   self._signs[ 'vimspectorPC' ],
+                                   frame[ 'line' ],
+                                   frame[ 'source' ][ 'path' ] ) )
 
     return True
 
@@ -166,11 +166,11 @@ class CodeView( object  ):
                           'line={1} '
                           'name={2} '
                           'file={3}'.format(
-            sign_id,
-            breakpoint[ 'line' ],
-            'vimspectorBP' if breakpoint[ 'verified' ]
-                           else 'vimspectorBPDisabled',
-            file_name ) )
+                            sign_id,
+                            breakpoint[ 'line' ],
+                            'vimspectorBP' if breakpoint[ 'verified' ]
+                            else 'vimspectorBPDisabled',
+                            file_name ) )
 
 
   def BreakpointsAsQuickFix( self ):
diff --git a/python3/vimspector/debug_adapter_connection.py b/python3/vimspector/debug_adapter_connection.py
index 844bb23..73a4549 100644
--- a/python3/vimspector/debug_adapter_connection.py
+++ b/python3/vimspector/debug_adapter_connection.py
@@ -190,7 +190,7 @@ class DebugAdapterConnection( object ):
       assert self._state == 'READ_BODY'
       return
 
-    payload = str( self._buffer[ : content_length  ], 'utf-8' )
+    payload = str( self._buffer[ : content_length ], 'utf-8' )
     self._buffer = self._buffer[ content_length : ]
 
     # self._logger.debug( 'Message received (raw): %s', payload )
diff --git a/python3/vimspector/debug_session.py b/python3/vimspector/debug_session.py
index 581eb6b..5acef40 100644
--- a/python3/vimspector/debug_session.py
+++ b/python3/vimspector/debug_session.py
@@ -17,12 +17,9 @@ import logging
 import vim
 import json
 import os
-import functools
 import subprocess
 import shlex
 
-from collections import defaultdict
-
 from vimspector import ( breakpoints,
                          code,
                          debug_adapter_connection,
@@ -110,11 +107,11 @@ class DebugSession( object ):
     # set from an api call like SetLaunchParam( 'var', 'value' ), perhaps also a
     # way to load .vimspector.local.json which just sets variables
     self._variables = {
-      'dollar': '$', # HACK
+      'dollar': '$', # HACK. Hote '$$' also works.
       'workspaceRoot': self._workspace_root,
       'gadgetDir': install.GetGadgetDir( VIMSPECTOR_HOME, install.GetOS() )
     }
-    self._variables.update( 
+    self._variables.update(
       utils.ParseVariables( adapter.get( 'variables', {} ) ) )
     self._variables.update(
       utils.ParseVariables( configuration.get( 'variables', {} ) ) )
@@ -125,7 +122,7 @@ class DebugSession( object ):
 
     if not adapter:
       utils.UserMessage( 'No adapter configured for {}'.format(
-        configuration_name ), persist=True  )
+        configuration_name ), persist=True )
       return
 
     self._StartWithConfiguration( configuration, adapter )
@@ -174,7 +171,7 @@ class DebugSession( object ):
     # beeps and doesn't display the config selector. One option is to just not
     # display the selector and restart with the same opitons.
     if not self._configuration or not self._adapter:
-      return Start()
+      return self.Start()
 
     self._StartWithConfiguration( self._configuration, self._adapter )
 
@@ -420,7 +417,7 @@ class DebugSession( object ):
     atttach_config = adapter_config.get( 'attach' )
 
     if not atttach_config:
-        return
+      return
 
     if 'remote' in atttach_config:
       # FIXME: We almost want this to feed-back variables to be expanded later,
@@ -449,7 +446,7 @@ class DebugSession( object ):
       commands = self._GetCommands( remote, 'attach' )
 
       for command in commands:
-        cmd = ssh + command[:]
+        cmd = ssh + command[ : ]
 
         for index, item in enumerate( cmd ):
           cmd[ index ] = item.replace( '%PID%', pid )
@@ -483,7 +480,7 @@ class DebugSession( object ):
       commands = self._GetCommands( remote, 'run' )
 
       for index, command in enumerate( commands ):
-        cmd = ssh + command[:]
+        cmd = ssh + command[ : ]
         full_cmd = []
         for item in cmd:
           if isinstance( command_line, list ):
@@ -560,7 +557,7 @@ class DebugSession( object ):
     if request == "attach":
       self._PrepareAttach( adapter_config, launch_config )
     elif request == "launch":
-      # FIXME: This cmdLine hack is not fun. 
+      # FIXME: This cmdLine hack is not fun.
       self._PrepareLaunch( self._configuration.get( 'remote-cmdLine', [] ),
                            adapter_config,
                            launch_config )
diff --git a/python3/vimspector/install.py b/python3/vimspector/install.py
index 280b07b..3e6de8f 100644
--- a/python3/vimspector/install.py
+++ b/python3/vimspector/install.py
@@ -16,6 +16,7 @@
 import platform
 import os
 
+
 def GetOS():
   if platform.system() == 'Darwin':
     return 'macos'
@@ -24,9 +25,11 @@ def GetOS():
   else:
     return 'linux'
 
+
 def GetGadgetDir( vimspector_base, OS ):
   return os.path.join( os.path.abspath( vimspector_base ), 'gadgets', OS )
 
+
 def GetGadgetConfigFile( vimspector_base ):
   return os.path.join( GetGadgetDir( vimspector_base, GetOS() ),
                        '.gadgets.json' )
diff --git a/python3/vimspector/output.py b/python3/vimspector/output.py
index fbeedce..6ca0971 100644
--- a/python3/vimspector/output.py
+++ b/python3/vimspector/output.py
@@ -83,7 +83,7 @@ class OutputView( object ):
         self._ShowOutput( category )
 
   def ConnectionUp( self, connection ):
-      self._connection = connection
+    self._connection = connection
 
   def ConnectionClosed( self ):
     # Don't clear because output is probably still useful
@@ -166,7 +166,7 @@ class OutputView( object ):
         if cmd is not None:
           out, err = utils.SetUpCommandBuffer( cmd, category )
           self._buffers[ category + '-out' ] = TabBuffer( out,
-                                                           len( self._buffers ) )
+                                                          len( self._buffers ) )
           self._buffers[ category + '-out' ].is_job = True
           self._buffers[ category + '-err' ] = TabBuffer( err,
                                                           len( self._buffers ) )
diff --git a/python3/vimspector/stack_trace.py b/python3/vimspector/stack_trace.py
index 61f1d64..9849131 100644
--- a/python3/vimspector/stack_trace.py
+++ b/python3/vimspector/stack_trace.py
@@ -38,7 +38,7 @@ class StackTraceView( object ):
     self._line_to_thread = {}
 
     # TODO: We really need a proper state model
-    # 
+    #
     # AWAIT_CONNECTION -- OnServerReady / RequestThreads --> REQUESTING_THREADS
     # REQUESTING -- OnGotThreads / RequestScopes --> REQUESTING_SCOPES
     #
@@ -76,7 +76,7 @@ class StackTraceView( object ):
     pending_request = False
     if self._requesting_threads:
       pending_request = True
-      return 
+      return
 
     def consume_threads( message ):
       self._requesting_threads = False
diff --git a/python3/vimspector/utils.py b/python3/vimspector/utils.py
index 4496e0e..6aad9e7 100644
--- a/python3/vimspector/utils.py
+++ b/python3/vimspector/utils.py
@@ -30,7 +30,7 @@ _log_handler.setFormatter(
 def SetUpLogging( logger ):
   logger.setLevel( logging.DEBUG )
   if _log_handler not in logger.handlers:
-      logger.addHandler( _log_handler )
+    logger.addHandler( _log_handler )
 
 
 def BufferNumberForFile( file_name ):
@@ -60,12 +60,12 @@ def SetUpCommandBuffer( cmd, name ):
 
   if bufs is None:
     raise RuntimeError( "Unable to start job {}: {}".format( cmd, name ) )
-  elif not all( [ b > 0 for b in bufs ] ):
+  elif not all( b > 0 for b in bufs ):
     raise RuntimeError( "Unable to get all streams for job {}: {}".format(
       name,
       cmd ) )
 
-  UserMessage( 'Bufs: {}'.format( [ int(b) for b in bufs ] ), persist = True )
+  UserMessage( 'Bufs: {}'.format( [ int( b ) for b in bufs ] ), persist = True )
 
   return [ vim.buffers[ b ] for b in bufs ]
 
@@ -257,11 +257,11 @@ def AppendToBuffer( buf, line_or_lines, modified=False ):
       buf.append( line_or_lines )
     elif isinstance( line_or_lines, str ):
       line = 1
-      buf[-1] = line_or_lines
+      buf[ -1 ] = line_or_lines
     else:
       line = 1
-      buf[:] = line_or_lines
-  except:
+      buf[ : ] = line_or_lines
+  except Exception:
     # There seem to be a lot of Vim bugs that lead to E315, whose help says that
     # this is an internal error. Ignore the error, but write a trace to the log.
     logging.getLogger( __name__ ).exception(
@@ -276,7 +276,7 @@ def AppendToBuffer( buf, line_or_lines, modified=False ):
 
 
 def ClearBuffer( buf ):
-  buf[:] = None
+  buf[ : ] = None
 
 
 def IsCurrent( window, buf ):
@@ -330,7 +330,7 @@ def ExpandReferencesInDict( obj, mapping, **kwargs ):
 
 def ParseVariables( variables ):
   new_variables = {}
-  for n,v in variables.items():
+  for n, v in variables.items():
     if isinstance( v, dict ):
       if 'shell' in v:
         import subprocess
diff --git a/python3/vimspector/variables.py b/python3/vimspector/variables.py
index a66bf57..7e2c9c9 100644
--- a/python3/vimspector/variables.py
+++ b/python3/vimspector/variables.py
@@ -93,7 +93,7 @@ class VariablesView( object ):
       utils.ClearBuffer( self._watch.win.buffer )
 
   def ConnectionUp( self, connection ):
-      self._connection = connection
+    self._connection = connection
 
   def ConnectionClosed( self ):
     self.Clear()