Fix unclosed file warning

    str_one = "Step "

    if filename[-3:] == ".gz":

      txt = gzip.open(filename, 'rt').read()

      with gzip.open(filename, 'rt') as f:

        txt = f.read()

    else:

      txt = open(filename, 'rt').read()

      with open(filename, 'rt') as f:

        txt = f.read()

    if txt.find(str_multi) >= 0:

      self.firststr = str_multi