old_contents: import os
  from ConfigParser import SafeConfigParser
  
  class Driver(object):
      def __init__(self):
          self.base_path = os.path.dirname(os.path.abspath(__file__))
          config_filename = "drivers.conf"
          self.config_path = os.path.join(self.base_path, config_filename)
          if os.path.exists(self.config_path):
              try:
                  self.parser = SafeConfigParser()
                  self.parser.read(self.config_path)
              except IOError:
                  print "ERROR opening config file: {}".format(config_filename)
                  sys.exit(1)
          else:
              print "ERROR: config.ini not found! Exiting!"
              sys.exit(1)
  
      def acquire_access_token(self, guest=False):
          pass
  
      def connect(self, include_guest=False):
          pass
  
      def download(self, remote_filename, local_filename):
          pass
  
      def upload(self, local_filename, remote_filename):
          pass
  
      def share(self, host_filename, guest_filename):
          pass
  
new_contents: import os
  from ConfigParser import SafeConfigParser
  
  class Driver(object):
      def __init__(self):
          """load configuration file"""
          self.base_path = os.path.dirname(os.path.abspath(__file__))
          config_filename = "drivers.conf"
          self.config_path = os.path.join(self.base_path, config_filename)
          if os.path.exists(self.config_path):
              try:
                  self.parser = SafeConfigParser()
                  self.parser.read(self.config_path)
              except IOError:
                  print "ERROR opening config file: {}".format(config_filename)
                  sys.exit(1)
          else:
              print "ERROR: config.ini not found! Exiting!"
              sys.exit(1)
  
      def acquire_access_token(self, guest=False):
          raise NotImplementedError()
  
      def connect(self, include_guest=False):
          raise NotImplementedError()
  
      def download(self, remote_filename, local_filename):
          raise NotImplementedError()
  
      def upload(self, local_filename, remote_filename):
          raise NotImplementedError()
  
      def share(self, host_filename, guest_filename):
          raise NotImplementedError()
  
  
subject: raise NotImplementedError in abstract methods