@classmethod
def available(cls, cmd_binary=None):
    """
        Class method that reports whether the command binary is
        available.
        """
    if cmd_binary is None:
        cmd_binary = cls.cmd_binary
    if not cmd_binary:
        return False
    try:
        cls._execute(cmd_binary=cmd_binary)
    except OSError:
        return False
    return True
