HydPy_branch needs strictly monotonous input data for xpoints. But in some cases it might be wanted to define stepwise discontinous functions for branching models (or at least derive smoothened functions from step functions). One use case might be if all runoff between 0 and 10 m³/s should go to outlet 1, but if there are more than 10 m³/s incoming 90% are going to outlet 1 and 10% to outlet 2. Maybe it would be useful to define the relation of input and outputs by ppolytools