Remove some attributes from a subject.

def DeleteAttributes(self,
                       subject,
                       attributes,
                       start=None,
                       end=None,
                       sync=True):
    """Remove some attributes from a subject."""
    _ = sync  # Unused
    if not attributes:
      return

    if isinstance(attributes, string_types):
      raise ValueError(
          "String passed to DeleteAttributes (non string iterable expected).")

    for attribute in attributes:
      timestamp = self._MakeTimestamp(start, end)
      attribute = utils.SmartUnicode(attribute)
      queries = self._BuildDelete(subject, attribute, timestamp)
      self._ExecuteQueries(queries)