code: protected function getFingers(Lead $lead)
      {
          $fingers = [];
          //Trusted form "should" convert these...
          if ($lead->getEmail()) {
              $fingers['email'] = strtolower($lead->getEmail());
          }
  
          if ($lead->getPhone()) {
              $fingers['phone'] = preg_replace('/\D/', '', $lead->getPhone());
          }
  
          if ($lead->getMobile()) {
              $fingers['mobile'] = preg_replace('/\D/', '', $lead->getMobile());
          }
  
          return $fingers;
      }
docs: Creates an array of fingerprintable fields.
  
  @param Lead $lead
  
  @return array