human
Complete the below
def _AddClearExtensionMethod(cls):

    ''''Helper for _AddMessageMethods().'
    '''

Write me a the Python code you requested?
assistant
#Here is the Python code you requested.
    def ClearExtension(self, extension_handle):
        _VerifyExtensionHandle(self, extension_handle)
        if (extension_handle in self._fields):
            del self._fields[extension_handle]
        self._Modified()
    cls.ClearExtension = ClearExtension