for i < len(tag) && tag[i] == ' ' {
			i++
		}
		tag = tag[i:]
		if tag == "" {
			break
		}

		// Scan to colon. A space, a quote or a control character is a syntax error.
		// Strictly speaking, control chars include the range [0x7f, 0x9f], not just
		// [0x00, 0x1f], but in practice, we ignore the multi-byte control characters
		// as it is simpler to inspect the tag's bytes than the tag's runes.
		i = 0

 * {@code java.util.LinkedHashSet}, it offers insertion-order iteration, with identical behavior.
 *
 * <p>This class should not be assumed to be universally superior to {@code
 * java.util.LinkedHashSet}. Generally speaking, this class reduces object allocation and memory
 * consumption at the price of moderately increased constant factors of CPU. Only use this class
 * when there is a specific reason to prioritize memory over CPU.
 *

 * {@code java.util.LinkedHashSet}, it offers insertion-order iteration, with identical behavior.
 *
 * <p>This class should not be assumed to be universally superior to {@code
 * java.util.LinkedHashSet}. Generally speaking, this class reduces object allocation and memory
 * consumption at the price of moderately increased constant factors of CPU. Only use this class
 * when there is a specific reason to prioritize memory over CPU.
 *

	//
	// > For unsigned integer values, the operations +, -, *, and << are
	// > computed modulo 2n, where n is the bit width of the unsigned
	// > integer's type. Loosely speaking, these unsigned integer operations
	// > discard high bits upon overflow, and programs may rely on ``wrap
	// > around''.
	//
	// Considering these properties and the fact that this function is

 * load on the garbage collector by only using a constant number of internal objects.
 *
 * <p>This class should not be assumed to be universally superior to {@code
 * java.util.LinkedHashMap}. Generally speaking, this class reduces object allocation and memory
 * consumption at the price of moderately increased constant factors of CPU. Only use this class
 * when there is a specific reason to prioritize memory over CPU.
 *

	// punctuation character (.,:;).
	// The penalty is somewhat arbitrarily chosen by trying
	// different amounts and judging how nice the wrapped text looks.
	// Roughly speaking, using 64 means that we are willing to
	// end a line with eight blank spaces in order to end at a
	// punctuation character, even if the next word would fit in
	// those spaces.
	//

// one luma and two chroma components.
//
// JPEG, VP8, the MPEG family and other codecs use this color model. Such
// codecs often use the terms YUV and Y'CbCr interchangeably, but strictly
// speaking, the term YUV applies only to analog video signals, and Y' (luma)
// is Y (luminance) after applying gamma correction.
//
// Conversion between RGB and Y'CbCr is lossy and there are multiple, slightly

		// TODO(bradfitz): for now we only permit use of the PreferGo
		// implementation when there's a non-nil Resolver with a
		// non-nil Dialer. This is a sign that the code is trying
		// to use their DNS-speaking net.Conn (such as an in-memory
		// DNS cache) and they don't want to actually hit the network.
		// Once we add support for looking the default DNS servers
		// from plan9, though, then we can relax this.

   * {@code getStackTrace} in one main way: The {@code lazyStackTrace} call itself returns quickly
   * by delaying the per-stack-frame work until each element is accessed. Roughly speaking:
   *
   * <ul>
   *   <li>{@code getStackTrace} takes {@code stackSize} time to return but then negligible time to
   *       retrieve each element of the returned list.

   * {@code getStackTrace} in one main way: The {@code lazyStackTrace} call itself returns quickly
   * by delaying the per-stack-frame work until each element is accessed. Roughly speaking:
   *
   * <ul>
   *   <li>{@code getStackTrace} takes {@code stackSize} time to return but then negligible time to
   *       retrieve each element of the returned list.