def __contains__(self, ext):
        """Checks if the given extension is in the known extensions. This is
        especially useful for clients to check if a server offers a certain
        desired extension, e.g. ``if 'AUTH' in extensions:``.

        :param ext: The extension to check for, case-insensitive.
        :rtype: True or False

        """
        return ext.upper() in self.extensions
dataset/ETHPy150Open slimta/python-slimta/slimta/smtp/extensions.py/Extensions.__contains__/original