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(texinfo)expansion

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`@expansion{}' (==>): Indicating an Expansion
---------------------------------------------

  When an expression is a macro call, it expands into a new expression.
You can indicate the result of the expansion with the `@expansion{}'
command.

  The `@expansion{}' command is displayed as `==>' in Info and as a
long arrow with a flat base in the printed output.

  For example, the following

     @lisp
     (third '(a b c))
          @expansion{} (car (cdr (cdr '(a b c))))
          @result{} c
     @end lisp

produces

     (third '(a b c))
          ==> (car (cdr (cdr '(a b c))))
          => c

which may be read as:

     `(third '(a b c))' expands to `(car (cdr (cdr '(a b c))))'; the
     result of evaluating the expression is `c'.

Often, as in this case, an example looks better if the `@expansion{}'
and `@result{}' commands are indented five spaces.