import gzip


def read_kmers(kmerfile):
    """
    Simply reads input file with kmers, ony by line.
    :param kmerfile: path to file with kmers to read
    :return kmers: set of kmers
    """

    with gzip.open(kmerfile, 'rt') as inf:
        kmers = {x.strip() for x in inf}

    return kmers