code: function() {
          if (!this._displayCallerInfo && !_globalDisplayCallerInfo) {
              return "";
          }
          else {
              var callerFrame = (new Error()).stack.split('\n')[3];
              // Got the line number trick from:
              // https://github.com/igo/nlogger
              // in the file:
              // https://github.com/igo/nlogger/blob/master/lib/nlogger.js
              var lineNumber = callerFrame.split(':')[1];
              // Made up the filename trick based on the above.
              var fileName = path.basename(callerFrame.split(/\(|\:/g)[1]);
              return "("+fileName+":"+lineNumber+") ";
          }
      }
docs: What line number called this logger method?
  NOTE: This method is designed to be called from within a logger
  function and will not work as expected if called outside of the
  logger.