docs: function indent(str, indent) {
              if (typeof indent === 'number') {
                  var indent_str = '';
                  while (indent_str.length < indent) indent_str += ' ';
                  indent = indent_str;
              }
              var lines = str.split(/\n/);
              for (var i=0; i<lines.length; i++) {
                  if (lines[i].trim() !== '')
                      lines[i] = indent + lines[i];
              }
              return lines.join("\n");            
          }