code: def command(state, args):
      
      args = parser.parse_args(args[1:])
      aid = state.results.parse_aid(args.aid, default_key='db')
      if args.query:
          # Use regexp provided by user.
          regexp = '.*'.join(args.query)
      else:
          # Make default regexp.
          title = query.select.lookup(state.db, aid, fields=['title']).title
          # Replace non-word, non-whitespace with whitespace.
          regexp = re.sub(r'[^\w\s]', ' ', title)
          # Split on whitespace and join with wildcard regexp.
          regexp = '.*?'.join(re.escape(x) for x in regexp.split())
          # Append episode matching regexp.
          regexp = '.*?'.join((
              regexp,
              r'\b(?P<ep>[0-9]+)(v[0-9]+)?',
          ))
      query.files.set_regexp(state.db, aid, regexp)
docs: Register watching regexp for an anime.