def boolArg(v):
    """Own boolean type for arguments, which converts a string into a bool.

    Provide it as type in add_argument.
    """
    if isinstance(v, bool):
        return v
    if v.lower() in ('yes', 'true', 't', 'y', '1'):
        return True
    elif v.lower() in ('no', 'false', 'f', 'n', '0'):
        return False
    else:
        raise ValueError('Boolean value expected.')
