simp only [removeAssignment, hb, addAssignment, ite_true]
case pos
assignment : Assignment
b : Bool
h : ¬hasAssignment b assignment = true
hb : b = true
⊢ removeAssignment b (addAssignment b assignment) = assignment
case pos
assignment : Assignment
b : Bool
h : ¬hasAssignment b assignment = true
hb : b = true
⊢ assignment.addPosAssignment.removePosAssignment = assignment