3.23 Blocks: block
The bindings documented in this section are provided by the racket/block library, not racket/base or racket.
(block defn-or-expr ...)
Supports a mixture of expressions and mutually recursive definitions, as in a module body. Unlike an internal-definition context, the last defn-or-expr need not be an expression.
The final defn-or-expr is executed in tail position, if it is an expression.