def make_doc_func(fnm):
    """
    Construct a trivial function with a docstring that includes a
    specified call graph image
    """

    def doc_fun(*args):
        pass

    doc_fun.__doc__ = """

        **Call graph**

        .. image:: _static/jonga/%s
           :width: 20%%
           :target: _static/jonga/%s\n""" % (fnm, fnm)

    return doc_fun