_ = append(s, "foo"...)
	_ = append(S(s), "foo" /* ERRORx `cannot use .* in argument to append` */ )
	_ = append(S(s), "foo"...)
	_ = append(s, t /* ERROR "cannot use t" */ )
	_ = append(s, t...)
	_ = append(s, T("foo")...)
	_ = append(S(s), t /* ERROR "cannot use t" */ )
	_ = append(S(s), t...)
	_ = append(S(s), T("foo")...)
	_ = append([]string{}, t /* ERROR "cannot use t" */ , "foo")
	_ = append([]T{}, t, "foo")
}

Leonardo Sarra <******@****.***> 1718116194 +0200

Leonardo Sarra <******@****.***> 1718116194 +0200

Leonardo Sarra <******@****.***> 1718116194 +0200

Leonardo Sarra <******@****.***> 1718116194 +0200

Leonardo Sarra <******@****.***> 1718116194 +0200

Leonardo Sarra <******@****.***> 1718116194 +0200

        ["1"]       | _             | _             | "append missing, then add"                        | { it.append(notDefined()) ; it.add("1") }
        ["1"]       | ["0"]         | _             | "add missing to non-empty value, then append"     | { it.add(notDefined()) ; it.append("1") }

	s := string(p.buf)
	p.free()
	return s
}

// Appendln formats using the default formats for its operands, appends the result
// to the byte slice, and returns the updated slice. Spaces are always added
// between operands and a newline is appended.
func Appendln(b []byte, a ...any) []byte {
	p := newPrinter()
	p.doPrintln(a)
	b = append(b, p.buf...)
	p.free()
	return b
}

	if x >= 0x1000 {
		b = append(b, digits[x>>12])
	}
	if x >= 0x100 {
		b = append(b, digits[x>>8&0xf])
	}
	if x >= 0x10 {
		b = append(b, digits[x>>4&0xf])
	}
	return append(b, digits[x&0xf])
}

// appendHexPad appends the fully padded hex string representation of x to b.
func appendHexPad(b []byte, x uint16) []byte {