docs: def iter(self):
          """
          Iterate over the sequences in the files in self.files_, yielding each
          as an instance of the desired read class.
          """
          for _file in self._files:
              with asHandle(_file) as fp:
                  # Use FastqGeneralIterator because it provides access to
                  # the unconverted quality string (i.e., it doesn't try to
                  # figure out the numeric quality values, which we don't
                  # care about at this point).
                  for sequenceId, sequence, quality in FastqGeneralIterator(fp):
                      yield self.readClass(sequenceId, sequence, quality)