stack/stack.go
func (c *Call) similar(r *Call, similar Similarity) bool {
	return c.SrcPath == r.SrcPath && c.Line == r.Line && c.Func == r.Func && c.Args.similar(&r.Args, similar)
}
func (c *Call) similar(r *Call, similar Similarity) bool {
	return c.SrcPath == r.SrcPath && c.Line == r.Line && c.Func == r.Func && c.Args.similar(&r.Args, similar)
}
// similar returns true if the two Call are equal or almost but not quite
// equal.