Formal verification of Rust code using Creusot and the Pearlite specification language. Use when the user wants to (1) add contracts/specifications to Rust functions, (2) prove correctness of Rust code, (3) write loop invariants, (4) use Creusot's Why3-based verification, (5) work with Pearlite syntax (requires, ensures, invariant, logic, predicate), or (6) debug failing Creusot proofs. Triggers include "verify this Rust", "prove", "Creusot", "add contracts", "formal verification", "loop invariant", "precondition", "postcondition", "Pearlite".