Configure a translation framework for a service provider

(src_lng, tar_lng, text2translate, API_KEY, endpoint) => { 
 //src_lang: source language 
 //tar_lang: target language 
 //text2translate: text to send for translation 
 //API_KEY: API key from your service provider 
 //endpoint: endpoint/API URL of your service provider 
 //build your query  
 var query:Function = //REST API goes here, which returns a Promise 
 return { 
  caller: query  
 } 
}

(src_lng, tar_lng, text2translate, API_KEY, endpoint) => { 
     const uuidv4 = require('uuid/v4'); 
   const request = require('request'); 
 var api_request_fn = () => { 
   // return a promise because sending and receiving translated text is asynchronous procedure 
            return new Promise((resolve, reject) => {  
   var request_data = { 
              method: 'POST', 
              baseUrl: endpoint, 
              url: 'translate', 
              qs: { 
                'api-version': '3.0', 
                'to': [tar_lng] 
              }, 
              headers: { 
                 'Ocp-Apim-Subscription-Key': API_KEY, //your API key goes here 
                 'Content-type': 'application/json', 
                 'X-ClientTraceId': uuidv4().toString() //give an ID to your request 
              }, 
              body: [{ 
                    'text': text2translate //send the text to translate as a part of the body 
              }], 
              json: true, 
          }  
   // the structure of request_data is different for every service provider 
   // look up the documentation provided by your translation service provider  
   // to build the request data. 
 
                request(request_data, function(err, res, body) {  
     // read about request method here https://www.npmjs.com/package/request 
                    if(err) {// in case of an error reject the promise, it will exit the translation process 
                        reject({body, err, res}) 
                    } else {// in case of a valid response from the server, resolve the promise 
                        resolve({body, err, res}) 
                    } 
                }) 
            }).then(data => { 
                if(data.body.error) { 
     // in case error from the server is send as part of the body  
     // and skipping the previous if block in request, handle it here  
                    throw new Error(data.body.error.message); 
     // throw the error with the message you want to show,  
     // preferably the error message sent by the server 
                } else { 
                    return data.body[0].translations[0].text  
     // return the translated text here, in this case it is in the data at  
     // the specified location. The location in the data object varies with the provider 
                } 
            }) 
        } 
}