old_contents: """
  Library for the robot based system test tool of the OpenDaylight project.
  Authors: Baohua Yang@IBM, Denghui Huang@IBM
  Updated: 2013-11-14
  """
  import collections
  
  # Global variables
  DEFAULT_CONTROLLER_IP = '127.0.0.1'
  #DEFAULT_CONTROLLER_IP = '9.186.105.113' #just for temp test
  DEFAULT_PORT = '8080'
  DEFAULT_PREFIX = 'http://' + DEFAULT_CONTROLLER_IP + ':' + DEFAULT_PORT
  DEFAULT_CONTAINER = 'default'
  DEFAULT_USER = 'admin'
  DEFAULT_PWD = 'admin'
  MODULES_DIR = 'modules'
  TIMEOUTS = 2
  
  '''
  Common constants and functions for the robot framework.
  '''
  
  def collection_should_contain(collection, *members):
      """
      Fail if not every members is in the collection.
      """
      if not isinstance(collection, collections.Iterable):
          return False
      for m in members:
          if m not in collection:
              return False
      else:
          return True
  
  if __name__ == '__main__':
      pass
  
new_contents: """
  Library for the robot based system test tool of the OpenDaylight project.
  Authors: Baohua Yang@IBM, Denghui Huang@IBM
  Updated: 2013-11-14
  """
  import collections
  
  # Global variables
  DEFAULT_CONTROLLER_IP = '127.0.0.1'
  #DEFAULT_CONTROLLER_IP = '9.186.105.113' #just for temp test
  DEFAULT_PORT = '8080'
  DEFAULT_PREFIX = 'http://' + DEFAULT_CONTROLLER_IP + ':' + DEFAULT_PORT
  DEFAULT_CONTAINER = 'default'
  DEFAULT_USER = 'admin'
  DEFAULT_PWD = 'admin'
  MODULES_DIR = 'modules'
  TIMEOUTS = 2
  
  '''
  Common constants and functions for the robot framework.
  '''
  
  def collection_should_contain(collection, *members):
      """
      Fail if not every members is in the collection.
      """
      if not isinstance(collection, collections.Iterable):
          return False
      for m in members:
          if m not in collection:
              return False
      else:
          return True
  
  def combine_strings(strings):
      """
      Combines the given `strings` together and returns the result.
      The given strings are not altered by this keyword.
      """
      result = ''
      for s in strings:
          if isinstance(s,str):
              result += s
      if result == '':
          return None
      else:
          return result
  
  if __name__ == '__main__':
      pass
  
subject: Add the combine_strings keyword.