def cma_on_space(function_space, arguments):
    """ Returns the corresponding argument if the supplied list of arguments
    contains a cma operator that maps to/from the specified space. Otherwise
    returns None."""
    if function_space.mangled_name in arguments.unique_fs_names:
        for arg in arguments.args:
            if (arg.type == 'gh_columnwise_operator' and function_space.
                orig_name in [arg.function_space_to.orig_name, arg.
                function_space_from.orig_name]):
                return arg
    return None
