from operator import add


def addLists(lst1, lst2):
    """Return the elementwise sum of lst1 and lst2.

    >>> addLists([1, 2, 3],[4, 5, 6])
    [5, 7, 9]
    """
    assert len(lst1) == len(lst2), "The lists have to be the same length."
    return list(map(add, lst1, lst2))