Create(func : GeneralFunction; exp : GeneralExpression)
---Purpose: Creates me as <func>(<exp>).
-- Raises exception if <func> is not unary.
- returns mutable UnaryFunction
+ returns UnaryFunction
raises InvalidFunction;
Function(me)
Copy(me)
---Purpose: Returns a copy of <me> having the same unknowns and functions.
- returns mutable like me;
+ returns like me;
IsIdentical(me; Other : GeneralExpression)
---Purpose: Tests if <me> and <Other> define the same expression.