question: build the graph . calling any method including this method on this builder object after calling this method is undefined behaviour . concode_field_sep G graph concode_field_sep B addVertices concode_elem_sep B removeEdge concode_elem_sep UnmodifiableGraph<V,E> buildUnmodifiable concode_elem_sep B removeVertex concode_elem_sep B self concode_elem_sep B addEdgeChain concode_elem_sep B addVertex concode_elem_sep B addEdge concode_elem_sep B addGraph concode_elem_sep B removeVertices
target: G function ( ) { return this . graph ; }