code: public void addRegularColumns(float left, float right, float gutterWidth, int numColumns) {
          float currX = left;
          float width = right - left;
          float colWidth = (width - (gutterWidth * (numColumns - 1))) / numColumns;
          for (int i = 0; i < numColumns; i++) {
              addSimpleColumn(currX, currX + colWidth);
              currX += colWidth + gutterWidth;
          }
      }
docs: Add the specified number of evenly spaced rectangular columns.
  Columns will be separated by the specified gutterWidth.
  
  @param left        left boundary of first column
  @param right       right boundary of last column
  @param gutterWidth width of gutter spacing between columns
  @param numColumns  number of columns to add