First and last name detection

{
  "formatVersion": "2",
  "dialogue": {
    "file": "main.dsl"
  },
  "nlu": {
    "language": "en-US",
    "skills": [
        "person-en:v2"
    ],
    "customIntents": {
      "file": "nlu.json"
    }
  },
  "nlg": {
    "type": "phrases",
    "file": "phrasemap.json",
    "signatureFile": "phrasemap.json"
  },
  "name": "my app name"
}

context {
  input endpoint: string;
  output first_name: string? = null;
  output last_name: string? = null;
}

start node root 
{
    do //actions executed in this node 
    {
        #connectSafe($endpoint); // connecting to the phone number which is specified in index.js that it can also be in-terminal text chat
        goto ask;
    }
    transitions // specifies to which nodes the conversation goes from here 
    {
        ask: goto ask;
    }
}

node ask 
{
    do {
        if ($first_name is null and $last_name is null) {
            #sayText("What is your name?");
            wait *;
        }          
        #sayText("Thank you, have a good day!");
        exit;
    } 
    transitions {
        ask: goto ask on true;
    }
}

preprocessor digression get_first_name 
{
    conditions { on #messageHasData("first_name"); }
    do {
        set $first_name = #messageGetData("first_name")[0]?.value;
        return;
    }
}

preprocessor digression get_last_name {
    conditions { on #messageHasData("last_name"); }
    do {
        set $last_name = #messageGetData("last_name")[0]?.value;
        return;
    }
}