f(ev.node, false)
			}
		}
		i++
	}
}

// WithStack visits nodes in a similar manner to Nodes, but it
// supplies each call to f an additional argument, the current
// traversal stack. The stack's first element is the outermost node,
// an *ast.File; its last is the innermost, n.
func (in *Inspector) WithStack(types []ast.Node, f func(n ast.Node, push bool, stack []ast.Node) (proceed bool)) {

	// skip the traversal.
	if !analysisutil.Imports(pass.Pkg, "net/http") {
		return nil, nil
	}

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}
	inspect.WithStack(nodeFilter, func(n ast.Node, push bool, stack []ast.Node) bool {
		if !push {
			return true
		}
		call := n.(*ast.CallExpr)
		if !isHTTPFuncOrMethodOnClient(pass.TypesInfo, call) {

	}

	// Maps each cancel variable to its defining ValueSpec/AssignStmt.
	cancelvars := make(map[*types.Var]ast.Node)

	// TODO(adonovan): opt: refactor to make a single pass
	// over the AST using inspect.WithStack and node types
	// {FuncDecl,FuncLit,CallExpr,SelectorExpr}.

	// Find the set of cancel vars to analyze.
	stack := make([]ast.Node, 0, 32)
	ast.Inspect(node, func(n ast.Node) bool {
		switch n.(type) {