def without_piecewise(expr):
    """
    Removes the Piecewise from an expression by assuming that all restricting assumptions are false.
    """
    if not expr.args:
        return expr

    if expr.is_Piecewise:
        return without_piecewise(expr.args[-1].expr)

    return expr.func(*[without_piecewise(a) for a in expr.args])