// 1
parameterRegex.matchEntire(toParse)?.run {
    require(groupValues.size == 3)
    val (parameter, value, rest) = destructured
    parameters[parameter] = value
    return parse(rest)
}

// 2
parameterRegex.matchEntire(toParse)?.let {
    require(it.groupValues.size == 3)
    val (parameter, value, rest) = it.destructured
    parameters[parameter] = value
    return parse(rest)
}

return

// 1
parameterRegex.matchEntire(toParse)?.run {
    require(groupValues.size == 3)
    val (parameter, value, rest) = destructured
    parameters[parameter] = value
    parse(rest)
}