code: def string_to_uuid(value, strict=True):
      
      try:
          return None if is_undefined(value) else uuid.UUID(value)
      except ValueError, error:
          if strict:
              raise error
docs: Return a Universally Unique Identifier (UUID) object represented by
      the specified string.
  
      @param value: a string representation of a UUID.
      @param strict: indicate whether the specified string MUST be of a
          valid UUID representation.
  
      @return: a UUID object.