### 5.12.4 Force evaluation : unquote

unquote is used to evaluate inside a quoted expression.
For example in an affectation, the variable is automatically quoted (not evaluated) so that the user does not have to quote it explicitly each time he want to modify its value. In some circumstances, you might however want to evaluate it.
Input:

purge(b);a:=b;unquote(a):=3

Output :

b contains 3, hence a evals to 3