is
Create(name : AsciiString)
- returns mutable NamedUnknown;
+ returns NamedUnknown;
IsAssigned(me)
---Purpose: Tests if an expression is assigned to <me>.
Copy(me)
---Purpose: Returns a copy of <me> having the same unknowns and functions.
- returns mutable like me;
+ returns like me;
ContainsUnknowns(me)
---Purpose: Tests if <me> contains NamedUnknown.