def extract_commands() ->dict:
    """Lists the available sub-commands of the 'chado extract' command with corresponding descriptions"""
    return {'organisms': 'list all organisms in the CHADO database',
        'cvterms': 'list all CV terms in the CHADO database',
        'gene_products':
        'list all products of transcripts in the CHADO database',
        'annotation_updates': 'list annotation updates in a CHADO database',
        'curator_comments':
        'list curator comments to genes and gene products in a CHADO database'}
