pick (props, keys) {
    return keys.reduce((map, key) => {
      map[key] = props[key]
      return map
    }, {})
  }
Return a shallow copy of the provided object, but only include the
properties specified in `keys`.

@example
import { utils } from 'js-data';
const a = { name: 'John', $hashKey: 1214910 };

let b = utils.pick(a, ['$hashKey']);
console.log(b); // { $hashKey: 1214910 }

@method utils.pick
@param {object} props The object to copy.
@param {string[]} keys Array of strings, representing properties to keep.
@returns {Object} Shallow copy of `props`, but only including `keys`.
@since 3.0.0