code: static boolean isAlive(Vertex vertex) {
          if (vertex == null) return false;
  
          try {
              return Sets.newHashSet(Schema.BaseType.values()).contains(Schema.BaseType.valueOf(vertex.label()));
          } catch (IllegalStateException e) {
              return false;
          }
      }
docs: The state of the vertex in the database. This may detect ghost nodes and allow them to be excluded from
  computations. If the vertex is alive it is likely to be a valid Grakn concept.
  
  @return if the vertex is alive