text: #ifndef RIVULET_FILTER_H
  #define RIVULET_FILTER_H
  
  #include "RivuletStream.h"
  
  typedef Boolean (*rivulet_filter_function) (int);
  RivuletStream *rivulet_stream_filter (RivuletStream *, rivulet_stream_filter_function);
  
  #endif //RIVULET_FILTER_H
  