# Hillel Wayne - A Simple Spec :: Learn TLA+ (Highlights)  ## Highlights - ---- MODULE module\_name ---- \* TLA+ code (* --algorithm algorithm\_name begin \* PlusCal code end algorithm; *) ==== - You can only have one PlusCal algorithm per file. - In the `variables` block, `=` is assignment. Everywhere else, `=` is the equality check and `:=` is assignment. - `TLC` is a module that adds `print` and `assert`. - `A:`. That is called a *label*. TLC treats labels as the “steps” in a specification - It’s only between labels that the model can check invariants and switch processes. - you can’t assign to the same variable twice in the same label. - While - This is the only form of looping. - You might have noticed the `y \in {3, 4}`. - TLC will make sure it works for **all** possible values of y. Create multiple behaviors