def reverseComplement(seq, alphabet='ACGT'):
    """
    Returns the reverse complement of nucleic acid sequence input.
    """
    compl= dict(zip('ACGTNRYWSMKBHDV', 'TGCANYRWSKMVDHB'))
    return ''.join([compl[base]
                    for base in seq.upper().replace('U', 'T')])[::-1]