Distinct Elements

You are given an array $A$ containing $N$ integers. A [subsequence](https://en.wikipedia.org/wiki/Subsequence) of this array is called *good* if all the elements of this subsequence are distinct. Find the number of *good* non-empty subsequences of $A$. This number can be large, so report it modulo $10^9 + 7$. Note that two subsequences are considered different if they differ in the indices chose