code: function _trim(str, re) {
      if (_.isString(str)) {
          return str.replace(re, '');
      } else {
          util.type('trim', str, 'string');
          return str;
      }
  }
docs: Strips tabs, spaces, and newlines (all whitespace)
  from the left or right or both side of a string.
  which depends on second argument. if it is 'r' will only
  trim right side,if it is 'l' will only trim left side
  otherwise trim both left and right side.
  
  {{ '   some spaces   ' | trim }} => 'some spaces'
  {{ '   some spaces   ' | trimRight }} => '   some spaces'
  {{ '   some spaces   ' | trimLeft }} => 'some spaces   '