def purge():
    global _start_node
    global _end_node
    global _lines
    global _settings
    _start_node = None
    _end_node = None
    _lines = []
    _settings = {}
def purge():
    global _start_node
    global _end_node
    global _lines
    global _settings
    _start_node = None
    _end_node = None
    _lines = []
    _settings = {}