How to use @kind graph query?

[ox1234]

I use @kind graph query and got such error:

Here is my select:

[intrigus-lgtm]

The query as you have written requires @kind path-problem and not @kind graph.

Documentation on the usage of @kind graph is hard to find, but it seems to work like this:
You have @kind graph as metadata and two query predicates. (You don't define any from, where, or select clause)
The first predicate defines the nodes of the graph and the second defines the edges.
The prototype of nodes is query predicate nodes(ANY_TYPE node, string attr, string val) and the prototype of edges is query predicate edges(ANY_TYPE pred, ANY_TYPE succ, string attr, string val)
See here for some kind of example:

codeql/ruby/ql/test/library-tests/regexp/parse.ql

Lines 8 to 27 in 15caaa7

	query predicate nodes(RETV::RegExpTerm n, string attr, string val) {
	attr = "semmle.label" and
	val = "[" + concat(n.getAPrimaryQlClass(), ", ") + "] " + n.toString()
	or
	attr = "semmle.order" and
	val =
	any(int i |
	n =
	rank[i](RETV::RegExpTerm t, string fp, int sl, int sc |
	t.hasLocationInfo(fp, sl, sc, _, _)
	|
	t order by fp, sl, sc
	)
	).toString()
	}
	query predicate edges(RETV::RegExpTerm pred, RETV::RegExpTerm succ, string attr, string val) {
	attr in ["semmle.label", "semmle.order"] and
	val = any(int i | succ = pred.getChild(i)).toString()
	}

[ox1234]

Thanks for a lot, but i'm still don't understand the meaning of attr and val.

[ox1234]

Do i need to define all showed nodes in nodes predicate?
I write following ql to draw the call graph from the entry, but i don't get any edges in generated .dot file

query predicate nodes(InterestringCallable node, string attr, string val){
    exists(node) and attr = "semmle.label" and val = getCallableSig(node)
}

query predicate edges(Callable pred, Callable succ, string attr, string val){
    succ = pred.getACallee() and
    attr in ["semmle.label"] and
    val = getCallableSig(succ)
}

[ox1234]

I draw a graph successfully, thanks a lot for your help😊