old_contents: import os
  import sqlite3
  import json
  import lz4
  
  
  class Feature:
  
      description = '(no description)'
  
      def __init__(self, firefed):
          self.ff = firefed
          self.args = None
  
      def __call__(self, args):
          self.args = args
          self.run()
  
      def run(self):
          raise NotImplementedError('Features need to implement run()!')
  
      def profile_path(self, path):
          return os.path.join(self.ff.profile_dir, path)
  
      def load_json(self, path):
          with open(self.profile_path(path)) as f:
              data = json.load(f)
          return data
  
      def load_sqlite(self, db_path, table, cls):
          def obj_factory(cursor, row):
              dict_ = {}
              for idx, col in enumerate(cursor.description):
                  new_name = cls._column_map[col[0]]
                  dict_[new_name] = row[idx]
              return cls(**dict_)
          con = sqlite3.connect(self.profile_path(db_path))
          con.row_factory = obj_factory
          cursor = con.cursor()
          result = cursor.execute('SELECT %s FROM %s' %
                                  (','.join(cls._column_map), table)).fetchall()
          return result
          con.close()
          return result
  
      def load_moz_lz4(self, path):
          with open(self.profile_path(path), 'rb') as f:
              if f.read(8) != b'mozLz40\0':
                  raise Exception('Not Mozilla lz4 format.')
              data = lz4.block.decompress(f.read())
          return data
  
      def add_arguments(parser):
          pass
  
  
  class SqliteTableFeature:
  
      def run(self):
          con = sqlite3.connect(self.profile_path(self.db_file))
          cursor = con.cursor()
          num = cursor.execute(
              'SELECT COUNT(*) FROM %s' % self.table_name).fetchone()[0]
          print(self.num_text % num + '\n')
          if self.args.summarize:
              return
          result = cursor.execute('SELECT %s FROM %s' %
                                  (','.join(self.fields), self.table_name)).fetchall()
          self.process_result(result)
  
      def process_result(self, result):
          raise NotImplementedError()
  
new_contents: import os
  import sqlite3
  import json
  import lz4
  
  
  class Feature:
  
      description = '(no description)'
  
      def __init__(self, firefed):
          self.ff = firefed
          self.args = None
  
      def __call__(self, args):
          self.args = args
          self.run()
  
      def run(self):
          raise NotImplementedError('Features need to implement run()!')
  
      def profile_path(self, path):
          return os.path.join(self.ff.profile_dir, path)
  
      def load_json(self, path):
          with open(self.profile_path(path)) as f:
              data = json.load(f)
          return data
  
      def load_sqlite(self, db_path, table, cls):
          def obj_factory(cursor, row):
              dict_ = {}
              for idx, col in enumerate(cursor.description):
                  new_name = cls._column_map[col[0]]
                  dict_[new_name] = row[idx]
              return cls(**dict_)
          con = sqlite3.connect(self.profile_path(db_path))
          con.row_factory = obj_factory
          cursor = con.cursor()
          result = cursor.execute('SELECT %s FROM %s' %
                                  (','.join(cls._column_map), table)).fetchall()
          con.close()
          return result
  
      def load_moz_lz4(self, path):
          with open(self.profile_path(path), 'rb') as f:
              if f.read(8) != b'mozLz40\0':
                  raise Exception('Not Mozilla lz4 format.')
              data = lz4.block.decompress(f.read())
          return data
  
      def add_arguments(parser):
          pass
  
  
  class SqliteTableFeature:
  
      def run(self):
          con = sqlite3.connect(self.profile_path(self.db_file))
          cursor = con.cursor()
          num = cursor.execute(
              'SELECT COUNT(*) FROM %s' % self.table_name).fetchone()[0]
          print(self.num_text % num + '\n')
          if self.args.summarize:
              return
          result = cursor.execute('SELECT %s FROM %s' %
                                  (','.join(self.fields), self.table_name)).fetchall()
          self.process_result(result)
  
      def process_result(self, result):
          raise NotImplementedError()
  
subject: Remove redundant return