This node takes the Union of two sets and returns the resulting set
After the bbsa places all of the non-terminal nodes, this funciton is called to place the terminal nodes at the bottom of the parse tree
This function generates the code for this node for the external verification
This node saves a snapshot of the set that is passed into it
After the bbsa places all of the non-terminal nodes, this funciton is called to place the terminal nodes at the bottom of the parse tree
This function generates the code for this node for the external verification