varName -
Symbol identifying the variable to be modified.
value -
The object for wich the variable will hold a reference.
Returns:
The news contents of the variable, that is, a reference to
value object.
Changes the contents of a variable accessible in the currente
context. A reference to the object passed as the value
is stored in the variable identified by the symbol
varName. The function set! does not
create new variables. The variable must have already been created.
If that is not the case a runtime exception is thrown. New variables
can be created using the define function.
