lib/update.js
function update (state, prefix, objectsOrIds, change) {
  if (typeof objectsOrIds !== 'object' && !change) {
    return Promise.reject(
      new Error('Must provide change')
    )
  }

  return Array.isArray(objectsOrIds)
    ? updateMany(state, objectsOrIds, change, prefix)
    : updateOne(state, objectsOrIds, change, prefix)
}
function update (state, prefix, objectsOrIds, change) {
  if (typeof objectsOrIds !== 'object' && !change) {
    return Promise.reject(
      new Error('Must provide change')
    )
  }

  return Array.isArray(objectsOrIds)
    ? updateMany(state, objectsOrIds, change, prefix)
    : updateOne(state, objectsOrIds, change, prefix)
}
function update ( state , prefix , objectsOrIds , change ) { if ( typeof objectsOrIds !== 'object' && ! change ) { return Promise . reject ( new Error ( 'Must provide change' ) ) } return Array . isArray ( objectsOrIds ) ? updateMany ( state , objectsOrIds , change , prefix ) : updateOne ( state , objectsOrIds , change , prefix ) }
updates existing object.

@param  {String}                   prefix        optional id prefix
@param  {String|Object|Object[]}   objectsOrIds  id or object (or array of objects) with `._id` property
@param  {Object|Function}          [change]      Changed properties or function
that changes existing object
@return {Promise}
updates existing object .