Example: TWICE

Takes any number of forms and evaluates them all once and then all again.

> (defmacro twice (&rest forms)

> (append '(progn) forms forms) )

TWICE

> (twice (format t "Macros are powerful~%")

> (format t "Aren’t they?~%") )

Macros are powerful

Aren’t they?

Macros are powerful

Aren’t they?

NIL

>

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