// Literal method needs to scan the pattern.
		re := MustCompile(tc.pattern)
		str, complete := re.LiteralPrefix()
		if complete != tc.isLiteral {
			t.Errorf("LiteralPrefix(`%s`) = %t; want %t", tc.pattern, complete, tc.isLiteral)
		}
		if str != tc.literal {
			t.Errorf("LiteralPrefix(`%s`) = `%s`; want `%s`", tc.pattern, str, tc.literal)
		}
	}
}

type subexpIndex struct {

			sz := l.sizeEstimate(*target)

			// Worst case size is where is that a separator of "" is used, and each char is returned as a list element.
			max := sz.Max
			if len(args) > 1 {
				if v := args[1].Expr().AsLiteral(); v != nil {
					if i, ok := v.Value().(int64); ok {
						max = uint64(i)
					}
				}
			}
			// Cost is the traversal plus the construction of the result.