def pubmlst_schemas(pubmlst_file):
    """Read the PubMLST mappings and return a dict."""
    pubmlst = {}
    with open(pubmlst_file, 'rt') as pubmlst_fh:
        for line in pubmlst_fh:
            line = line.rstrip()
            if line and not line.startswith('ariba'):
                ariba, species, schema = line.split('\t')
                if species not in pubmlst:
                    pubmlst[species] = {}
                pubmlst[species][schema] = ariba
    return pubmlst