Get HLA alleles from the hg38 fasta fai file.

def read_hlas(fasta_fai):
    """Get HLA alleles from the hg38 fasta fai file.
    """
    out = []
    with open(fasta_fai) as in_handle:
        for line in in_handle:
            if line.startswith("HLA"):
                out.append(line.split()[0])
    return out