docs: def top(**kwargs):
      '''
      Connect to a mongo database and read per-node tops data.
  
      Parameters:
          * `collection`: The mongodb collection to read data from. Defaults to
            ``'tops'``.
          * `id_field`: The field in the collection that represents an individual
            minion id. Defaults to ``'_id'``.
          * `re_pattern`: If your naming convention in the collection is shorter
            than the minion id, you can use this to trim the name.
            `re_pattern` will be used to match the name, and `re_replace` will
            be used to replace it. Backrefs are supported as they are in the
            Python standard library. If ``None``, no mangling of the name will
            be performed - the collection will be searched with the entire
            minion id. Defaults to ``None``.
          * `re_replace`: Use as the replacement value in node ids matched with
            `re_pattern`. Defaults to ''. Feel free to use backreferences here.
          * `states_field`: The name of the field providing a list of states.
          * `environment_field`: The name of the field providing the environment.
            Defaults to ``environment``.
      '''
      host = __opts__['mongo.host']
      port = __opts__['mongo.port']
      collection = __opts__['master_tops']['mongo'].get('collection', 'tops')
      id_field = __opts__['master_tops']['mongo'].get('id_field', '_id')
      re_pattern = __opts__['master_tops']['mongo'].get('re_pattern', '')
      re_replace = __opts__['master_tops']['mongo'].get('re_replace', '')
      states_field = __opts__['master_tops']['mongo'].get('states_field', 'states')
      environment_field = __opts__['master_tops']['mongo'].get('environment_field', 'environment')
  
      log.info('connecting to %s:%s for mongo ext_tops', host, port)
      conn = pymongo.MongoClient(host, port)
  
      log.debug('using database \'%s\'', __opts__['mongo.db'])
      mdb = conn[__opts__['mongo.db']]
  
      user = __opts__.get('mongo.user')
      password = __opts__.get('mongo.password')
  
      if user and password:
          log.debug('authenticating as \'%s\'', user)
          mdb.authenticate(user, password)
  
      # Do the regex string replacement on the minion id
      minion_id = kwargs['opts']['id']
      if re_pattern:
          minion_id = re.sub(re_pattern, re_replace, minion_id)
  
      log.info(
          'ext_tops.mongo: looking up tops def for {\'%s\': \'%s\'} in mongo',
          id_field, minion_id
      )
  
      result = mdb[collection].find_one({id_field: minion_id}, projection=[states_field, environment_field])
      if result and states_field in result:
          if environment_field in result:
              environment = result[environment_field]
          else:
              environment = 'base'
          log.debug('ext_tops.mongo: found document, returning states')
          return {environment: result[states_field]}
      else:
          # If we can't find the minion the database it's not necessarily an
          # error.
          log.debug('ext_tops.mongo: no document found in collection %s', collection)
          return {}