def str2bool(x):
    """Converts a string to boolean type.
    
    If the string is any of ['no', 'false', 'f', '0'], or any capitalization,
    e.g. 'fAlSe' then returns False. All other strings are True.

    """
    if x is None or x.lower() in ['no', 'false', 'f', '0']:
        return False
    else:
        return True