code: function toSource(func) {
    if (func != null) {
      try {
        return funcToString$2.call(func);
      } catch (e) {}
      try {
        return (func + '');
      } catch (e) {}
    }
    return '';
  }
docs: Converts `func` to its source code.
  
  @private
  @param {Function} func The function to convert.
  @returns {string} Returns the source code.