|  NodeAssign (const string& varid, BinOper* mod, Node* rvalue, unsigned line)
 | NodeAssign | 
Caller must not delete / modify pointer.
Parameters:
| varid | the name of the variable being assigned to. | 
| mod | the modifier (e.g., += has a modifier OpAdd). | 
| rvalue | the expression being assigned to the variable. | 
| line | line of configuration where node was created. | 
|  ~NodeAssign ()
 | ~NodeAssign | 
|  DEFINE_VISITABLE ()
 | DEFINE_VISITABLE | 
| const string&  varid ()
 | varid | 
[const]
Returns: name of variable being assigned to.
| Node&  rvalue ()
 | rvalue | 
[const]
Returns: argument of assignment.
| BinOper*  mod ()
 | mod | 
[const]