text: """Compatibility layer for Python version 2.x and 3.x.
  """
  
  import sys
  
  PY_VER = sys.version_info[0]
  
  if PY_VER >= 3:
      import pickle
      from urllib.request import urlopen
      from urllib.error import HTTPError
      STRING_BASE_CLASS = str
  else:
      import cPickle as pickle
      from urllib2 import urlopen, HTTPError
      STRING_BASE_CLASS = basestring
  
  def unicode_str(x=''):
      return str(x) if PY_VER == 3 else unicode(x, encoding='utf-8')
  