code: def rename(self, columns):
          
          new_data = OrderedDict()
          for column_name in self:
              if column_name in columns.keys():
                  column = self._data[column_name]
                  new_name = columns[column_name]
                  new_data[new_name] = Series(column.values, column.index, column.dtype, new_name)
              else:
                  new_data[column_name] = self._data[column_name]
  
          return DataFrame(new_data, self.index)
docs: Returns a new DataFrame with renamed columns.
  
          Currently a simplified version of Pandas' rename.
  
          Parameters
          ----------
          columns : dict
              Old names to new names.
  
          Returns
          -------
          DataFrame
              With columns renamed, if found.