Problem exporting function from node.js

I'm a beginner in node.js and I created an API that validates a CPF and returns a value of true or false, but I'm not able to send the return of that function to my other application. Here is the code:

                            export default function discourseHandler(r) {
                              if (r.context.cpf){ 
                                function is_cpf (c) {

                                  if((c = String(c).replace(/[^\d]/g,"")).length != 11)
                                    return false;

                                  if (c == "00000000000" ||
                                    c == "11111111111" ||
                                    c == "22222222222" ||
                                    c == "33333333333" ||
                                    c == "44444444444" ||
                                    c == "55555555555" ||
                                    c == "66666666666" ||
                                    c == "77777777777" ||
                                    c == "88888888888" ||
                                    c == "99999999999") 
                                        return false; 

                                  var r;
                                  var s = 0;   
                                  var i;
                                  for (i=1; i<=9; i++)
                                    s = s + parseInt(c[i-1]) * (11 - i); 

                                  r = (s * 10) % 11;

                                  if ((r == 10) || (r == 11)) 
                                    r = 0;

                                  if (r != parseInt(c[9]))
                                    return false; 

                                  s = 0;

                                  for (i = 1; i <= 10; i++)
                                    s = s + parseInt(c[i-1]) * (12 - i);

                                  r = (s * 10) % 11;

                                  if ((r == 10) || (r == 11)) 
                                    r = 0;

                                  if (r != parseInt(c[10]))
                                    return false;

                                  return true;
                                }

                              is_cpf (r.context.cpf);
                              r.context.cpf =  is_cpf();
                              }

                              return r;

                            }