promql/ast.go
func Inspect(node Node, f inspector) {
	Walk(inspector(f), node, nil)
}
func Inspect(node Node, f inspector) {
	Walk(inspector(f), node, nil)
}
func Inspect ( node Node , f inspector ) { Walk ( inspector ( f ) , node , nil ) }
// Inspect traverses an AST in depth-first order: It starts by calling
// f(node, path); node must not be nil. If f returns a nil error, Inspect invokes f
// for all the non-nil children of node, recursively.
Inspect traverses an AST in depth - first order : It starts by calling f ( node path ) ; node must not be nil . If f returns a nil error Inspect invokes f for all the non - nil children of node recursively .