node.py

class Node:
    def __init__(self):
        self.a = 0.0
        self.b = 0.0
        self.c = [7.0, 4.7]

    def __str__(self):
        s = ""
        for k, v in self.__dict__.items():
            s += str(k) + ":" + str(v) + "\n"
        return s

def main():
    n1 = Node()
    print(n1)

if __name__=="__main__":
    main()