code: def _mod(field, value, document):
      
      try:
          divisor, remainder = map(int, value)
      except (TypeError, ValueError):
          raise MalformedQueryException("'$mod' must accept an iterable: [divisor, remainder]")
  
      try:
          return int(document.get(field, None)) % divisor == remainder
      except (TypeError, ValueError):
          return False
docs: Performs a mod on a document field. Value must be a list or tuple with
      two values divisor and remainder (i.e. [2, 0]). This will essentially
      perform the following:
  
          document[field] % divisor == remainder
  
      If the value does not contain integers or is not a two-item list/tuple,
      a MalformedQueryException will be raised. If the value of document[field]
      cannot be converted to an integer, this will return False.