lojix/prolog/src/main/com/thesett/aima/logic/fol/prolog/VariableBindingStackFrame.java
public void free()
    {
        for (int i = 0; i < bindings.length; i++)
        {
            if (bindings[i] != null)
            {
                bindings[i].free();
                bindings[i] = null;
            }
        }
    }
public void free()
    {
        for (int i = 0; i < bindings.length; i++)
        {
            if (bindings[i] != null)
            {
                bindings[i].free();
                bindings[i] = null;
            }
        }
    }
Frees all variables held in this stack frame, and sets all the stack slots to <tt>null</tt>. Note that as the
stack slots are <tt>null</tt> the {@link #getStorageCell(StackVariable)} method will not return valid storage
cells any more. This method should therefore only be used to clean up the stack frame when it is no longer
needed.