docs: function Tributary( options ) {
  
      options = options || {};
  
      stream.Transform.call( this, { encoding: options.encoding } );
  
      this.getStream = options.getStream || function( filename, cb ) {
          return cb();
      };
  
      this._matcher = new Matcher( 
          options.placeholderStart || '<!-- include ',
          options.placeholderEnd !== undefined ? options.placeholderEnd : ' -->',
          options.maxPathLength,
          options.delimiter
      );
         
      this._tributaryState = {
          chunk: null,
          cursor: 0,
          contentStart: 0,
          contentEnd: -1,
          remainder: 0
      };
   
  }