return nil
	}
	var callerAncestors []ancestorInfo
	if callergp.ancestors != nil {
		callerAncestors = *callergp.ancestors
	}
	n := int32(len(callerAncestors)) + 1
	if n > debug.tracebackancestors {
		n = debug.tracebackancestors
	}
	ancestors := make([]ancestorInfo, n)
	copy(ancestors[1:], callerAncestors)

	var pcs [tracebackInnerFrames]uintptr