PFNGLTRANSFORMFEEDBACKVARYINGSPROCDart typedef
        PFNGLTRANSFORMFEEDBACKVARYINGSPROCDart =
     void Function(int program, int count, Pointer<Pointer<Int8> >  varyings, int bufferMode)
    
    
    
Implementation
typedef PFNGLTRANSFORMFEEDBACKVARYINGSPROCDart =
    void Function(
      int program,
      int count,
      Pointer<Pointer<Int8>> varyings,
      int bufferMode,
    );