def METHOD_NAME(method_name, meta_arg, metadata):
    '''Utility method to initialise the required class variables and then
    call the method specified in the method_name argument.
    :param str method_name: the name of the method to call.
    :param meta_arg: the meta_arg metadata to pass to the call.
    :type meta_arg: subclass of \
        :py:class:`psyclone.domain.lfric.kernel.CommonArgMetadata`
    :param metadata: the full metadata description.
    :type metadata: \
        :py:class:`psyclone.domain.lfric.kernel.LFRicKernelMetadata`
    :returns: an ArgIndexToMetadataIndex class
    :rtype: :py:class:`psyclone.domain.lfric.ArgIndexToMetadataIndex`
    '''
    metadata.validate()
    cls = ArgIndexToMetadataIndex
    cls._initialise(None)
    cls._metadata = metadata
    getattr(cls, method_name)(meta_arg)
    return cls