asa = Person.find('https://example.com/asa')
    ric = Person.find('https://example.com/ric')
    ric.knows = asa.uri

    ric.eager_load_predicate_triples! #does a big DESCRIBE statement behind the scenes
    knows = ric.get_related_resource('https://example.com/knows', Resource)
    knows.label # this won't cause another database lookup

    ric.eager_load_object_triples! #does a big DESCRIBE statement behind the scenes
    asa = ric.get_related_resource('https://example.com/asa', Person) # returns a fully hydrated Person object for asa, without an extra lookup

    class Resource
      include Tripod::Resource
      field :label, RDF::RDFS.label

      # notice also that you don't need to supply an rdf type or graph here!
    end

    r = Resource.new('https://example.com/foo', 'https://example.com/mygraph')
    r.label = "example"
    r.save

    # Note: Tripod assumes you want to store all resources in named graphs.
    # So if you don't supply a graph at any point (i.e. class or instance level),
    # you will get an error when you try to persist the resource.

    r.write_predicate(RDF.type, 'https://example.com/myresource/type')
    r.read_predicate(RDF.type) #=> [RDF::URI.new("https://example.com/myresource/type")]

    # A Tripod::Criteria object defines a set of constraints for a SPARQL query.
    # It doesn't actually do anything against the DB until you run resources, first, or count on it.
    # (from Tripod::CriteriaExecution)

    Person.all #=> returns a Tripod::Criteria object which selects all resources of rdf_type https://example.com/person, in the https://example.com/people graph

    Resource.all #=> returns a criteria object to return resources in the database (as no rdf_type or graph_uri specified at class level)

    Person.all.resources #=> returns all the actual resources for the criteria object, as an array-like object

    Person.all.resources(:return_graph => false) #=> returns the actual resources, but without returning the graph_uri in the select (helps avoid pagination issues). Note: doesn't set the graph uri on the instantiated resources.

    Person.first #=> returns the first person (by crafting a sparql query under the covers that only returns 1 result)

    Person.first(:return_graph => false) # as with resources, doesn't return / set the graph_uri.

    Person.count  #=> returns the count of all people (by crafting a count query under the covers that only returns a count)

    # note that you need to use ?uri as the variable for the subject.
    Person.where("?uri <https://example.com/name> 'Joe'") #=> returns a Tripod::Criteria object

    Resource.graph("https://example.com/mygraph") #=> Retruns a criteria object with a graph restriction (note: if graph_uri set on the class, it will default to using this)

    Resource.find_by_sparql('SELECT ?uri ?graph WHERE { GRAPH ?graph { ?uri ?p ?o } }') #=> allows arbitrary sparql. Again, use ?uri for the variable of the subjects (and ?graph for the graph).

    Person.all.where("?uri <https://example.com/name> 'Ric'").where("?uri <https://example.com/knows> <https://example.com/asa>).first

    Person.where("?uri <https://example.com/name> ?name").limit(1).offset(0).order("DESC(?name)")