code: function trim(string, chars, guard) {
          string = toString(string);
          if (!string) {
            return string;
          }
          if (guard || chars === undefined) {
            return string.replace(reTrim, '');
          }
          chars = chars + '';
          if (!chars) {
            return string;
          }
          var strSymbols = stringToArray(string), chrSymbols = stringToArray(chars);
          return strSymbols.slice(charsStartIndex(strSymbols, chrSymbols), charsEndIndex(strSymbols, chrSymbols) + 1).join('');
        }
docs: Removes leading and trailing whitespace or specified characters from `string`.
  
  @static
  @memberOf _
  @category String
  @param {string} [string=''] The string to trim.
  @param {string} [chars=whitespace] The characters to trim.
  @param- {Object} [guard] Enables use as an iteratee for functions like `_.map`.
  @returns {string} Returns the trimmed string.
  @example
  
  _.trim('  abc  ');
  // => 'abc'
  
  _.trim('-_-abc-_-', '_-');
  // => 'abc'
  
  _.map(['  foo  ', '  bar  '], _.trim);
  // => ['foo', 'bar']