code: function() {
          var pieces = [];
          if(this.pretty) {
              for(var i=0; i<this.level; ++i) {
                  pieces.push(this.indent);
              }
          }
          return pieces.join('');
      }
docs: Method: writeIndent
  Output an indentation string depending on the indentation level.
  
  Returns:
  {String} An appropriate indentation string.