WRITE-ENVvoid [macro] (usually used just for outputting)
Within the context of a with-format, calls functions of
the format object, optionally with arguments. Typically these functions will output data to the
stream established by the with-format.
arguments:
function-calls(&rest)
Functions on the named output-format to be called
example:
(with-format (base-format my-object) (write-env (:a "Hello World, my object's length is: ")
(:a (the length))))