def fix_concept_id(category: str, cid: str) -> str:
    """
    Add prefix (if necessary) to concept id. Eliminate colons,
    e.g. in MESH:D015759. Pad id with one extra space before and after.
    :param category: concept category (Chemical, Disease, Gene, Species, etc.)
    :param cid:      concept id (MeSH id, NCBI gene or taxon id, etc.)
    :return:         fixed-up concept id
    """
    if category == 'Gene':
        return f' NCBIGene{cid} '
    elif category == 'SNP':
        return f' SNP{cid.lower()} '
    elif category == 'Species':
        return f' NCBITaxon{cid} '
    else:
        return f" {cid.replace(':', '')} "