code: def mk_set_headers(self, data, columns):
          
          columns = tuple(columns)
          lens = []
  
          for key in columns:
              value_len = max(len(str(each.get(key, ''))) for each in data)
              # account for header lengths
              lens.append(max(value_len, len(self._get_name(key))))
  
          fmt = self.mk_fmt(*lens)
          return fmt
docs: figure out sizes and create header fmt