def AddOrdinalSuffix(value):
    """Adds an ordinal suffix to a non-negative integer (e.g. 1 -> '1st').

  Args:
    value: A non-negative integer.

  Returns:
    A string containing the integer with a two-letter ordinal suffix.
  """
    if value < 0 or value != int(value):
        raise ValueError('argument must be a non-negative integer: %s' % value)
    if value % 100 in (11, 12, 13):
        suffix = 'th'
    else:
        rem = value % 10
        if rem == 1:
            suffix = 'st'
        elif rem == 2:
            suffix = 'nd'
        elif rem == 3:
            suffix = 'rd'
        else:
            suffix = 'th'
    return str(value) + suffix
