stylizeLine(left, content, right) {
    left = this.wrapWithStyleColors('border', left);
    right = this.wrapWithStyleColors('border', right);
    if (this.y === 0) {
      content = this.wrapWithStyleColors('head', content);
    }
    return left + content + right;
  }
Renders a line of text.
@param lineNum - Which line of text to render. This is not necessarily the line within the cell.
There may be top-padding above the first line of text.
@param drawRight - true if this method should render the right edge of the cell.
@param forceTruncationSymbol - `true` if the rendered text should end with the truncation symbol even
if the text fits. This is used when the cell is vertically truncated. If `false` the text should
only include the truncation symbol if the text will not fit horizontally within the cell width.
@param spanningCell - a number of if being called from a RowSpanCell. (how many rows below). otherwise undefined.
@returns {String}