code: def getkey(mapping, value, default=None, use_id=False):
      '''Returns the first key mapping to value, as encountered via iteritems(), otherwise default.  Obviously, works best for injective maps.
      '''
      if use_id:
          for key, val in mapping.items():
              if val is value:
                  return key
      else:
          for key, val in mapping.items():
              if val == value:
                  return key
      return defaulf getkey(mapping, value, default=None, use_id=False):
      '''Returns the first key mapping to value, as encountered via iteritems(), otherwise default.  Obviously, works best for injective maps.
      '''
      if use_id:
          for key, val in mapping.items():
              if val is value:
                  return key
      else:
          for key, val in mapping.items():
              if val == value:
                  return key
      return default
docs: Returns the first key mapping to value, as encountered via iteritems(), otherwise default.  Obviously, works best for injective maps.