code: def get_filenames(root, prefix=u'', suffix=u''):
      
      return [fnm for fnm in os.listdir(root) if fnm.startswith(prefix) and fnm.endswith(suffix)]
docs: Function for listing filenames with given prefix and suffix in the root directory.
      
      Parameters
      ----------
      
      prefix: str
          The prefix of the required files.
      suffix: str
          The suffix of the required files
          
      Returns
      -------
      list of str
          List of filenames matching the prefix and suffix criteria.