Removes elements deep in the stack until the depth of the stack is exactly 16. The elements
are removed in such a way that the top 16 elements of the stack remain unchanged. If the stack
would otherwise contain more than 16 elements at the end of execution, then adding a call to this
function at the end will reduce the size of the public inputs that are shared with the verifier.
Input: Stack with 16 or more elements.
Output: Stack with only the original top 16 elements.
Cycles: 17 + 11 * overflow_words, where `overflow_words` is the number of words needed to drop.
## std::sys
| Procedure | Description |
| ----------- | ------------- |