mapCall (funcName, ...args) {
    this.data = this.getData().map(function (item) {
      return item[funcName](...args)
    })
    return this
  }
Return the result of calling the specified function on each item in this
collection's main index.

@example
const stringAges = UserCollection.query().mapCall('toString').run();

@method Query#mapCall
@param {string} funcName Name of function to call
@parama {...*} [args] Remaining arguments to be passed to the function.
@returns {Query} A reference to itself for chaining.
@since 3.0.0