safea abstractions

Author: Carolyn Zech

doc/src/challenges/0016-iter.md

@@ -32,7 +32,7 @@ Write and prove the contract for the safety of the following unsafe functions:
 |__iterator_get_unchecked | zip.rs|
 |get_unchecked| zip.rs|
 
-Prove the absence of UB for following safe functions:
+Prove the absence of undefined behavior for following safe abstractions:
 
 | Function | Defined in |
 |---------| ---------|