'Return relative paths to externally referenced files by the tool
described by file at `path`. External components should not assume things
about the structure of tool xml files (this is the tool\'s responsibility).'

@classmethod
def get_externally_referenced_paths(self, path):

    tree = raw_tool_xml_tree(path)
    root = tree.getroot()
    external_paths = []
    for code_elem in root.findall('code'):
        external_path = code_elem.get('file')
        if external_path:
            external_paths.append(external_path)
    external_paths.extend(imported_macro_paths(root))
    return external_paths
