import pandas as pd


def create_series(L1, L2):
    s1 = pd.Series(L1, index=['a', 'b', 'c'])
    s2 = pd.Series(L2, index=['a', 'b', 'c'])
    return (s1, s2)

def modify_series(s1, s2):
    s1['d'] = s2['b']
    del(s2['b'])
    return (s1, s2)

def main():
    s1, s2 = create_series([1, 2, 3], [4, 5, 6])
    s1, s2 = modify_series(s1, s2)
    print(s1+s2)


if __name__ == "__main__":
    main()
