is_property_graph(graph)

# Create a graph with 2 nodes
# (with `type` values) and a
# single edge (with a `rel`)
simple_property_graph <-
  create_graph() %>%
  add_node(
    type = "a",
    label = "first") %>%
  add_node(
    type = "b",
    label = "second") %>%
  add_edge(
    from = "first",
    to = "second",
    rel = "rel_1")

# This is indeed a property graph
# but to confirm this, use the
# `is_property_graph()` function
is_property_graph(simple_property_graph)

# If a `type` attribute is
# removed, then this graph will
# no longer be a property graph
simple_property_graph %>%
  set_node_attrs(
    node_attr = type,
    values = NA,
    nodes = 1) %>%
  is_property_graph()

# An empty graph will return FALSE
create_graph() %>%
  is_property_graph()