Assigning to an element of a <code>nil</code> map causes a
<a href="#Run_time_panics">run-time panic</a>.
</p>


<h3 id="Slice_expressions">Slice expressions</h3>

<p>
Slice expressions construct a substring or slice from a string, array, pointer
to array, or slice. There are two variants: a simple form that specifies a low
and high bound, and a full form that also specifies a bound on the capacity.
</p>

Assigning to an element of a <code>nil</code> map causes a
<a href="#Run_time_panics">run-time panic</a>.
</p>


<h3 id="Slice_expressions">Slice expressions</h3>

<p>
Slice expressions construct a substring or slice from a string, array, pointer
to array, or slice. There are two variants: a simple form that specifies a low
and high bound, and a full form that also specifies a bound on the capacity.
</p>

		start int
		end   int
	}
	spans := make([]span, 0, 32)

	// Find the field start and end indices.
	// Doing this in a separate pass (rather than slicing the string s
	// and collecting the result substrings right away) is significantly
	// more efficient, possibly due to cache effects.
	start := -1 // valid span start if >= 0
	for i := 0; i < len(s); {
		size := 1
		r := rune(s[i])
		if r >= utf8.RuneSelf {