if err != nil || numEntries < 0 || int(2*numEntries) < int(numEntries) {
		return nil, ErrHeader
	}

	// Parse for all member entries.
	// numEntries is trusted after this since a potential attacker must have
	// committed resources proportional to what this library used.
	if err := feedTokens(2 * numEntries); err != nil {
		return nil, err
	}