from collections import namedtuple

myNamedTuple = namedtuple('myNamedTuple',
    ['P1', 'P2', 'P3', 'P4', 'P5', 'P6'],
    defaults=[None, None, None, '', [], []])

if __name__ == '__main__':

    g = myNamedTuple(P1 = 'hello', P2 = 'world')
    h = myNamedTuple(P1 = 'good', P2 = 'morning')

    list1 = ['a','b']
    list2 = ['c','d']

    print("g.P5 1: " + str(g.__repr__()))
    print("h.P5 1: " + str(h.__repr__()))

    print("Expected: g.P5: []")
    print("Actual:   g.P5: " + str(g.P5))   
    print("Expected: h.P5: []")
    print("Actual:   h.P5: " + str(h.P5))    


    new_g_P5 = g.P5
    new_g_P5.extend(list1)
    g = g._replace(P5 = new_g_P5)

    print("g.P5 2: " + str(g.__repr__()))
    print("h.P5 2: " + str(h.__repr__()))

    print("Expected: g.P5: ['a', 'b']")
    print("Actual:   g.P5: " + str(g.P5))   
    print("Expected: h.P5: []")
    print("Actual:   h.P5: " + str(h.P5))


    new_g_P5 = g.P5
    new_g_P5.extend(list2)
    g = g._replace(P5 = new_g_P5)

    print("g.P5 3: " + str(g.__repr__()))
    print("h.P5 3: " + str(h.__repr__()))

    print("Expected: g.P5: ['a', 'b', 'c', 'd']")
    print("Actual:   g.P5: " + str(g.P5))   
    print("Expected: h.P5: []")
    print("Actual:   h.P5: " + str(h.P5))