PFNGLORTHOPROCDart typedef
        PFNGLORTHOPROCDart =
     void Function(double left, double right, double bottom, double top, double nearVal, double farVal)
    
    
    
Implementation
typedef PFNGLORTHOPROCDart =
    void Function(
      double left,
      double right,
      double bottom,
      double top,
      double nearVal,
      double farVal,
    );