Variables are names that serve has handles for objects.
If you wish to introduce a local variable into a method, then you must
list that variable between vertical bars in the method's definition
before the first statement:
method selector
| variable 1 ... variable n |
...
Local variables have local scope. Accordingly, a variable value
assigned in one method cannot interfere with a variable assignment or
parameter assignment in another method, even if the names happen
to be the same, and a variable established in one method cannot
be evaluated in another method.
All local variables are initialized to nil.
If you wish to assign a local variable, then use an assignment statement:
