a proxy method that adds the node n to the graph being tested . in case of immutablegraph implementations , this method should add n to the graph builder and build a newgraph with the current builder state . concode_field_sep String ERROR_ELEMENT_NOT_IN_GRAPH concode_elem_sep MutableGraph<Integer> graph concode_elem_sep String ERROR_SELF_LOOP concode_elem_sep String ERROR_ADDED_SELF_LOOP concode_elem_sep Integer N1 concode_elem_sep String ERROR_MODIFIABLE_SET concode_elem_sep Integer N4 concode_elem_sep String ERROR_NODE_NOT_IN_GRAPH concode_elem_sep Integer N5 concode_elem_sep Integer NODE_NOT_IN_GRAPH concode_elem_sep Integer N2 concode_elem_sep String NODE_STRING concode_elem_sep Integer N3 concode_field_sep void degree_isolatedNode concode_elem_sep void removeEdge_existingEdge concode_elem_sep void adjacentNodes_checkReturnedSetMutability concode_elem_sep boolean putEdge concode_elem_sep void successors_checkReturnedSetMutability concode_elem_sep void removeNode_queryAfterRemoval concode_elem_sep void predecessors_noPredecessors concode_elem_sep void removeNode_existingNode concode_elem_sep void validateGraphState concode_elem_sep void nodes_oneNode concode_elem_sep void outDegree_isolatedNode concode_elem_sep void successors_noSuccessors concode_elem_sep void adjacentNodes_oneEdge concode_elem_sep void inDegree_isolatedNode concode_elem_sep void removeNode_nodeNotPresent concode_elem_sep void assertNodeNotInGraphErrorMessage concode_elem_sep void init concode_elem_sep void nodes_noNodes concode_elem_sep void removeEdge_oneOfMany concode_elem_sep void removeEdge_edgeNotPresent concode_elem_sep void predecessors_checkReturnedSetMutability concode_elem_sep void predecessors_nodeNotInGraph concode_elem_sep void outDegree_nodeNotInGraph concode_elem_sep void successors_nodeNotInGraph concode_elem_sep void degree_nodeNotInGraph concode_elem_sep void adjacentNodes_nodeNotInGraph concode_elem_sep void addNode_newNode concode_elem_sep void inDegree_nodeNotInGraph concode_elem_sep MutableGraph<Integer> createGraph concode_elem_sep void adjacentNodes_noAdjacentNodes concode_elem_sep void nodes_checkReturnedSetMutability concode_elem_sep void degree_oneEdge concode_elem_sep void removeEdge_nodeNotPresent concode_elem_sep void removeNode_antiparallelEdges concode_elem_sep void validateGraph concode_elem_sep void addNode_existingNode