if sig, _ := under(x.typ).(*Signature); sig != nil && sig.TypeParams().Len() > 0 {
			// function instantiation
			return true
		}
	}

	// x should not be generic at this point, but be safe and check
	check.nonGeneric(nil, x)
	if x.mode == invalid {
		return false
	}

	// ordinary index expression
	valid := false
	length := int64(-1) // valid if >= 0
	switch typ := under(x.typ).(type) {
	case *Basic:

		if sig, _ := under(x.typ).(*Signature); sig != nil && sig.TypeParams().Len() > 0 {
			// function instantiation
			return true
		}
	}

	// x should not be generic at this point, but be safe and check
	check.nonGeneric(nil, x)
	if x.mode == invalid {
		return false
	}

	// ordinary index expression
	valid := false
	length := int64(-1) // valid if >= 0
	switch typ := under(x.typ).(type) {
	case *Basic:

	}
	// x.typ may be generic

	switch x.mode {
	case invalid:
		check.use(call.ArgList...)
		x.expr = call
		return statement

	case typexpr:
		// conversion
		check.nonGeneric(nil, x)
		if x.mode == invalid {
			return conversion
		}
		T := x.typ
		x.mode = invalid
		switch n := len(call.ArgList); n {
		case 0:

	}
	// x.typ may be generic

	switch x.mode {
	case invalid:
		check.use(call.Args...)
		x.expr = call
		return statement

	case typexpr:
		// conversion
		check.nonGeneric(nil, x)
		if x.mode == invalid {
			return conversion
		}
		T := x.typ
		x.mode = invalid
		switch n := len(call.Args); n {
		case 0:

				},
			},
		},
	}
)

func main() {
	genGeneric := flag.Bool("generic", false, "generate generic versions")
	genExp := flag.Bool("exp", false, "generate x/exp/slices versions")
	flag.Parse()

	var variants []Variant
	if *genExp {
		variants = expVariants
	} else if *genGeneric {
		variants = genericVariants
	} else {
		variants = traditionalVariants
	}