cl-tagbody is an autoloaded Lisp macro in `cl-macs.el'.

(cl-tagbody &rest LABELS-OR-STMTS)

Execute statements while providing for control transfers to labels.
Each element of LABELS-OR-STMTS can be either a label (integer or symbol)
or a `cons' cell, in which case it's taken to be a statement.
This distinction is made before performing macroexpansion.
Statements are executed in sequence left to right, discarding any return value,
stopping only when reaching the end of LABELS-OR-STMTS.
Any statement can transfer control at any time to the statements that follow
one of the labels with the special form (go LABEL).
Labels have lexical scope and dynamic extent.