x) + 1).replace(Heaviside(x), Heaviside(x, 1))
    Heaviside(x, 1) + 1

    See Also
    ========

    DiracDelta

    References
    ==========

    .. [1] https://mathworld.wolfram.com/HeavisideStepFunction.html
    .. [2] https://dlmf.nist.gov/1.16#iv

    Tr