human
I wrote the below code

    def usages_script():
        source = 'import    import_tree_for_usages.b.
   import_tree_for_usages.b.bar'
        return jedi.api.Script(source=source, line=1, column=len(source), sys_path=[os.path.dirname(os.path.abspath(__file__))])
    def module_script():
        source = 'import    import_tree_for_usages.a.
   import_tree_for_usages.a'
        return jedi.api.Script(source=source, line=1, column=len(source), sys_path=[os.path.dirname(os.path.abspath(__file__))])
    module = module_script().goto_definitions()[0]
    module_definition = module._name.get_root_context()
    usages_list = usages_with_additional_modules(usages_script(), set([module]))
    assert any([elt for elt in usages_list if (elt.module_name == 'a')]), 'Did    not    find    cross-module    usage    of    :func:`b.bar`    in    :mod:`a`.    Usages    list    was:    {}'.format(usages_list)

What's a good function header?
 ... Write me a Python program to find    cross-module    usage    of    :func:`b?
assistant
#Here is Python program to find    cross-module    usage    of    :func:`b.

def test_cross_module_usages():