docs: def _iter_blocks(self):
          """Iter input lines in blocks separated by blank lines."""
          lines = []
          for line in self._iter_unfolded_lines():
              if line:
                  lines.append(line)
              elif lines:
                  self.records_read += 1
                  yield lines
                  lines = []
          if lines:
              self.records_read += 1
              yield lines