Comment by blinks

For more concrete syntax, consider the following Python:

  >>> import re
  >>> route = re.compile(r'(?P<fb>^/foo/bar$)|(?P<fbd>^/foo/bar/\d+$)')
  >>> route.match('/foo/bar').groupdict()
  {'fb': '/foo/bar', 'fbd': None}
  >>> route.match('/foo/bar/1').groupdict()
  {'fb': None, 'fbd': '/foo/bar/1'}

If the fb group is set, act on the first route. If the fbd group is set, act on the second.