code: def iter(self):
          
          count = 0
          for _file in self._files:
              with asHandle(_file) as fp:
                  # Duplicate some code here so as not to test
                  # self._upperCase in the loop.
                  if self._upperCase:
                      for seq in SeqIO.parse(fp, 'fasta'):
                          read = self._readClass(seq.description,
                                                 str(seq.seq.upper()))
                          yield read
                          count += 1
                  else:
                      for seq in SeqIO.parse(fp, 'fasta'):
                          read = self._readClass(seq.description, str(seq.seq))
                          yield read
                          count += 1
docs: Iterate over the sequences in the files in self.files_, yielding each
          as an instance of the desired read class.