old_contents: /* @flow */
  import * as firebase from 'firebase/app'
  import 'firebase/auth'
  import 'firebase/database'
  import { all, select, call, put, takeLatest } from 'redux-saga/effects'
  import { hydrateSessionMeta } from 'actions'
  import type { SessionMeta } from 'types'
  
  function * loadSessionMeta (userSessionId: string, sessionId: string): Generator<*, *, *> {
    const getMeta = () => new Promise((resolve, reject) => {
      firebase.database().ref(`sessions/${sessionId}/name`).once('value')
        .then(response => resolve({
          name: response.val()
        }))
        .catch(reject)
    })
  
    const meta = yield call(getMeta)
    yield put(hydrateSessionMeta(userSessionId, meta))
  }
  
  function * loadAllMeta (): Generator<*, *, *> {
    const sessions = yield select(state => state.user.data.userSessions)
  
    yield all(
      Object.keys(sessions).map(key => call(loadSessionMeta, key, sessions[key].sessionId))
    )
  }
  
  export default function * loadMeta (): Generator<*, *, *> {
    yield takeLatest('HYDRATE_USER_DATA', loadAllMeta)
  }
  
new_contents: /* @flow */
  import * as firebase from 'firebase/app'
  import 'firebase/auth'
  import 'firebase/database'
  import { all, select, call, put, takeLatest } from 'redux-saga/effects'
  import { hydrateSessionMeta } from 'actions'
  
  function * loadSessionMeta (userSessionId: string, sessionId: string): Generator<*, *, *> {
    const getMeta = () => new Promise((resolve, reject) => {
      firebase.database().ref(`sessions/${sessionId}/name`).once('value')
        .then(response => resolve({
          name: response.val()
        }))
        .catch(reject)
    })
  
    const meta = yield call(getMeta)
    yield put(hydrateSessionMeta(userSessionId, meta))
  }
  
  function * loadAllMeta (): Generator<*, *, *> {
    const sessions = yield select(state => state.user.data.userSessions)
  
    yield all(
      Object.keys(sessions).map(key => call(loadSessionMeta, key, sessions[key].sessionId))
    )
  }
  
  export default function * loadMeta (): Generator<*, *, *> {
    yield takeLatest('HYDRATE_USER_DATA', loadAllMeta)
  }
  
subject: Fix linter error.