code: public void putValue(E row, E col, T value) {
  		ensureRowKey(row);
  		ensureColKey(col);
  		get(rowKeys.get(row)).set(colKeys.get(col), value);
  	}
docs: Sets the matrix entry specified by the given row and col keys.<br>
  This method sets the following content: Matrix[row,col]=value
  @param row Row-value of indexing type
  @param col Col-value of indexing type
  @param value Value that has to be inserted