def pick_western_most_start_node(req_g):
    """
    Sets START_NODE equal to western-most node
    Args:
        req_g (NetworkX Graph): graph of street network containing all required edges
    Returns:
        START_NODE (var): wester-most node
    """
    x = list(req_g.nodes(data=True))[0][1]['x']
    START_NODE = list(req_g.nodes(data=True))[0][0]
    for n in list(req_g.nodes(data=True)):
        if n[1]['x'] < x:
            x = n[1]['x']
            START_NODE = n[0]
    return START_NODE