def biofile(itisbio):
    """
    Returns string containing ".bio" or empty string depending on fasta sequence employed

    Parameters
    ----------
    itisbio : bool
        Contains information about the nature of fasta sequence.

    Returns
    -------
    bio_path : str
        Either ".bio" or empty string.

    """
    if itisbio:
        bio_path='.bio'
    else:
        bio_path=''

    return bio_path