code: public void eachNonZeroInRow(int i, VectorProcedure procedure) {
          VectorIterator it = nonZeroIteratorOfRow(i);
  
          while (it.hasNext()) {
              double x = it.next();
              int j = it.index();
              procedure.apply(j, x);
          }
      }
docs: Applies the given {@code procedure} to each non-zero element of the specified row of this matrix.
  
  @param i the row index.
  @param procedure the {@link VectorProcedure}.