def get_vt_graph(vt_list, tree_info, pdf=False):
    """get_vt_graph(vt_list: list of locator, tree_info:str)
    Load all vistrails in vt_list and dump their tree to tree_info.
    
    """
    result = []
    if is_running_gui():
        from vistrails.gui.vistrail_controller import VistrailController as \
             GUIVistrailController
        for locator in vt_list:
            try:
                (v, abstractions , thumbnails, mashups)  = load_vistrail(locator)
                controller = GUIVistrailController(v, locator, abstractions, 
                                                   thumbnails, mashups)
                if tree_info is not None:
                    from vistrails.gui.version_view import QVersionTreeView
                    version_view = QVersionTreeView()
                    version_view.scene().setupScene(controller)
                    if pdf:
                        base_fname = "graph_%s.pdf" % locator.short_filename
                        filename = os.path.join(tree_info, base_fname)
                        version_view.scene().saveToPDF(filename)
                    else:
                        base_fname = locator.short_filename % "graph_%s.png"
                        filename = os.path.join(tree_info, base_fname)
                        version_view.scene().saveToPNG(filename)
                    del version_view
                    result.append((True, ""))
            except Exception, e:
                result.append((False, debug.format_exception(e)))
    else:
        error_str = "Cannot save version tree figure when not " \
            "running in gui mode"
        debug.critical(error_str)
        result.append((False, error_str))
    return result

################################################################################
dataset/ETHPy150Open VisTrails/VisTrails/vistrails/core/console_mode.py/get_vt_graph/swapped operands of `%`