var genToPromise = require('@f/gen-to-promise')

genToPromise(function * () {
  var students = yield fetch('/students').then((res) => res.json())
  var studentIds = students.map((student) => student.id)
  var teachers = yield fetch('/teachers.of', {body: {students: studentIds}}).then((res) => res.json())
  return teachers
}).then(function (teachers) {
  // teachers of students
})