Answers
Dec 18, 2014 - 02:14 PM
it was introduced in Lesson 12 of 1+2
Dec 18, 2014 - 05:47 PM
Yup, i just see it in 12 now, no real explanation, it looks like they think it was introduced before already. It appears in the workouts of lesson 10, so that's why i was surprised because i had never seen it before!