code: def at(self, root):
          
          leafs = root.strip(" ").split('.')
          for leaf in leafs:
              if leaf:
                  self._json_data = self.__get_value_from_data(leaf, self._json_data)
          return self
docs: Set root where PyJsonq start to prepare
  
          :@param root
          :@type root: string
  
          :@return self
          :@throws KeyError