def double_integer(i):
    return i * 2
    
if __name__ == "__main__":
    assert double_integer(2) = 4
    assert double_integer(4) = 8
    assert double_integer(3) = 6
    assert double_integer(2.5) = 5
    assert double_integer(7) = 14
    assert double_integer(10) = 20
