def CopyToPosixTimestamp(self):
normalized_timestamp = self._GetNormalizedTimestamp()<EOL>if normalized_timestamp is None:<EOL><INDENT>return None<EOL><DEDENT>return int(normalized_timestamp)<EOL>
Copies the date time value to a POSIX timestamp.

        Returns:
          int: a POSIX timestamp in seconds or None if no timestamp is available.