'Return the rational (numerator / denominator) value at *value_offset*
in *stream_rdr* as a floating-point number. Only supports single
values at present.'

@classmethod
def _parse_value(cls, stream_rdr, offset, value_count, value_offset):

    if (value_count == 1):
        numerator = stream_rdr.read_long(value_offset)
        denominator = stream_rdr.read_long(value_offset, 4)
        return (numerator / denominator)
    else:
        return 'Multi-value    Rational    NOT    IMPLEMENTED'
