Syntax:
[begin_label:] REPEAT
    statement_list
UNTIL search_condition
END REPEAT [end_label]

The statement list within a REPEAT statement is repeated until the
search_condition is true. Thus, a REPEAT always enters the loop at
least once. statement_list consists of one or more statements.

A REPEAT statement can be labeled. end_label cannot be given unless
begin_label also is present. If both are present, they must be the
same.
