overflow and the resulting value exists and is deterministically defined
by the signed integer representation, the operation, and its operands.
Overflow does not cause a <a href="#Run_time_panics">run-time panic</a>.
A compiler may not optimize code under the assumption that overflow does
not occur. For instance, it may not assume that <code>x &lt; x + 1</code> is always true.
</p>


<h4 id="Floating_point_operators">Floating-point operators</h4>

	for i := 0; i < len(s); i++ {
		c := s[i]
		if c >= utf8.RuneSelf {
			isASCII = false
			break
		}
		hasLower = hasLower || ('a' <= c && c <= 'z')
	}

	if isASCII { // optimize for ASCII-only byte slices.
		if !hasLower {
			// Just return a copy.
			return append([]byte(""), s...)
		}
		b := bytealg.MakeNoZero(len(s))[:len(s):len(s)]
		for i := 0; i < len(s); i++ {
			c := s[i]

overflow and the resulting value exists and is deterministically defined
by the signed integer representation, the operation, and its operands.
Overflow does not cause a <a href="#Run_time_panics">run-time panic</a>.
A compiler may not optimize code under the assumption that overflow does
not occur. For instance, it may not assume that <code>x &lt; x + 1</code> is always true.
</p>

<h4 id="Floating_point_operators">Floating-point operators</h4>