reuse parser result in other delegate

Say I have a synthetic situation: number `n` says how many symbols `x` will be after this number. After that, I want to drop all other `x`s.

For example:
```kotlin
val digit by regexToken("\\d")
val n by literalToken("n")
val found by digit map {it.toInt()}
val result by found and (found times n) and -zeroOrMore(n)
//                       ^ can't do
```