code: static LabelId getVertexTypeId(Vertex vertex) {
          if (vertex.property(Schema.VertexProperty.THING_TYPE_LABEL_ID.name()).isPresent()) {
              return LabelId.of(vertex.value(Schema.VertexProperty.THING_TYPE_LABEL_ID.name()));
          }
          return LabelId.invalid();
      }
docs: The Grakn type property on a given Tinkerpop vertex.
  If the vertex is a {@link SchemaConcept}, return invalid {@link Label}.
  
  @param vertex the Tinkerpop vertex
  @return the type