function getPopulateChild(firebase, populate, id) {
  const childPath = populate.childParam ? `/${populate.childParam}` : ''
  const path = `${populate.root}/${id}${childPath}`
  return firebase
    .database()
    .ref()
    .child(path)
    .once('value')
    .then((snap) =>
      // Return id if population value does not exist
      snap.val()
    )
}
@private
@param {object} firebase - Internal firebase object
@param {object} populate - Object containing root to be populate
@param {object} populate.root - Firebase root path from which to load populate item
@param {string} id - String id
@returns {Promise} Resolves with populate child