code: function add (obj, name, value) {
    const previous = obj[name]
    if (previous) {
      const arr = [].concat(previous)
      arr.push(value)
      return arr
    } else return value
  }
docs: Return value of array of values.
  
  @param {Object} obj
  @param {String} name
  @param {Any} value
  @return {Any|Array}
  @api private