return reverse completment of read

def rev_c(read):
    """
    return reverse completment of read
    """
    rc = []
    rc_nucs = {'A':'T', 'T':'A', 'G':'C', 'C':'G', 'N':'N'}
    for base in read:
        rc.extend(rc_nucs[base.upper()])
    return rc[::-1]