Add a new input `new_input_var` to this computation, whose value is determined by `precomp`: a term over existing inputs. The visibility for `new_input_var` will be computed from the visibility of variables in `precomp`: there must be at most **one** non-public variable. The sort for `new_input_var` will be computed from `precomp`.
(&mut self, new_input_var: String, precomp: Term)
source not stored for this graph (policy: none)