def check_completeness(ISM):
    """
    Check if an ISM is fully corrected (no ambiguous bases)
    Parameters
    ----------
    ISM: str
        an ISM of interest
    Returns
    -------
    FLAG: boolean
        if fully corrected
    """
    for item in ISM:
        if item not in ['A', 'T', 'C', 'G', '-']:
            return False
    return True