code: public function renderWidget(array $fields, $customFieldOrClass, $documentType='html', $slug = null)
      {
          return $this->container->get('chill.custom_field.helper')
              ->renderCustomField($fields, $customFieldOrClass, $documentType, $slug);
      }
docs: Twig extension that is used to render the value of a custom field.
  
  The presentation of the value  is influenced by the document type.
  
  @param array $fields The array raw, as stored in the db
  @param CustomField|object|string $customFieldOrClass Either a customField OR a customizable_entity OR the FQDN of the entity
  @param string $documentType The type of the document (csv, html)
  @param string $slug The slug of the custom field ONLY necessary if the first argument is NOT a CustomField instance
  @return string HTML representation of the custom field value, as described in the CustomFieldInterface. Is HTML safe