code: public final int getMinArity() {
      // NOTE(nicksantos): There are some native functions that have optional
      // parameters before required parameters. This algorithm finds the position
      // of the last required parameter.
      int i = 0;
      int min = 0;
      for (Node n : getParameters()) {
        i++;
        if (!n.isOptionalArg() && !n.isVarArgs()) {
          min = i;
        }
      }
      return min;
    }
docs: Gets the minimum number of arguments that this function requires.