Lodash Library; dropWhile predicate function

In the Lodash Library exercises, "Implement _.dropWhile() ", step 35, bullet 2:
“The supplied predicate function takes three arguments: the current element, the current element index, and the whole array”.

What is this predicate function and where is it kept?
It seems sort of central to the exercise.


If you are to make a function that adds two numbers, you don’t get to ask “which numbers will I receive?”
Use what you receive, regardless of which it is.
The whole point of having a parameter for it is so that it can be different things.