def _datetup2int(date):
  """Convert (year, month, day) to integer representation.

  Args:
    date: Tuple of (year, month, day).

  Returns:
    an int of year * 1e4 + month * 1e2 + day.
  """
  dint = date[0] * 1e4
  dint += date[1] * 1e2 if date[1] else 0
  dint += date[2] if date[2] else 0
  return dint