// a named variable.
type config struct {
	// Filename for file-based output formats, stdout by default.
	Output string `json:"-"`

	// Display options.
	CallTree            bool    `json:"call_tree,omitempty"`
	RelativePercentages bool    `json:"relative_percentages,omitempty"`
	Unit                string  `json:"unit,omitempty"`
	CompactLabels       bool    `json:"compact_labels,omitempty"`

	// as the graph itself doesn't contain enough information to preserve full precision.
	visualMode := o.OutputFormat == Dot
	cumSort := o.CumSort

	// The call_tree option is only honored when generating visual representations of the callgraph.
	callTree := o.CallTree && (o.OutputFormat == Dot || o.OutputFormat == Callgrind)

	// First step: Build complete graph to identify low frequency nodes, based on their cum weight.

	// Comparisons.
	"drop_negative": helpText(
		"Ignore negative differences",
		"Do not show any locations with values <0."),

	// Graph handling options.
	"call_tree": helpText(
		"Create a context-sensitive call tree",
		"Treat locations reached through different paths as separate."),

	// Display options.
	"relative_percentages": helpText(

John Howard <******@****.***> 1658777447 +0000

func (ui *webInterface) stackView(w http.ResponseWriter, req *http.Request) {
	// Get all data in a report.
	rpt, errList := ui.makeReport(w, req, []string{"svg"}, func(cfg *config) {
		cfg.CallTree = true
		cfg.Trim = false
		cfg.Granularity = "filefunctions"
	})
	if rpt == nil {
		return // error already reported
	}

	// Make stack data and generate corresponding JSON.
	stacks := rpt.Stacks()

	addFilter("tagignore", cfg.TagIgnore)
	addFilter("tagshow", cfg.TagShow)
	addFilter("taghide", cfg.TagHide)

	ropt := &report.Options{
		CumSort:      cfg.Sort == "cum",
		CallTree:     cfg.CallTree,
		DropNegative: cfg.DropNegative,

		CompactLabels: cfg.CompactLabels,
		Ratio:         1 / cfg.DivideBy,

		NodeCount:    cfg.NodeCount,
		NodeFraction: cfg.NodeFraction,

	ObjNames          bool                       // Always preserve obj filename
	OrigFnNames       bool                       // Preserve original (eg mangled) function names

	CallTree     bool // Build a tree instead of a graph
	DropNegative bool // Drop nodes with overall negative values

	KeptNodes NodeSet // If non-nil, only use nodes in this set
}

// Nodes is an ordered collection of graph nodes.

	"pakistan":                             "\U0001f1f5\U0001f1f0",
	"palau":                                "\U0001f1f5\U0001f1fc",
	"palestinian_territories":              "\U0001f1f5\U0001f1f8",
	"palm_tree":                            "\U0001f334",
	"palms_up_together":                    "\U0001f932",
	"panama":                               "\U0001f1f5\U0001f1e6",
	"pancakes":                             "\U0001f95e",