message: Add ParametersSpec.set_function_name
  Summary: You can mutate the name of various things after construction with the ComplexValue.export_as. Often that will make sense to mutate the ParametersSpec too.
diff: @@ -133,6 +133,11 @@ impl<V> ParametersSpec<V> {
  }
  }
  + /// Change the function name.
  + pub fn set_function_name(&mut self, name: String) {
  + self.function_name = name
  + }
  +
  fn add(&mut self, name: &str, val: ParameterKind<V>) {
  let i = self.kinds.len();
  self.kinds.push(val);
  