diff --git a/google_vision.module b/google_vision.module
index 2c64af5..4737aac 100644
--- a/google_vision.module
+++ b/google_vision.module
@@ -10,6 +10,8 @@ use Drupal\field\FieldConfigInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityTypeInterface;
 use Drupal\taxonomy\Entity\Vocabulary;
+use Drupal\file\FileInterface;
+use Drupal\Core\Field\FieldDefinitionInterface;
 
 /**
  * Implements hook_entity_presave().
@@ -20,6 +22,7 @@ function google_vision_entity_presave(EntityInterface $entity) {
     // If it's image.
     if (in_array($mimetype, ['image/jpeg', 'image/png', 'image/jpg'])) {
       // Try to find fields which should be used for Google labels.
+      /** @var FieldDefinitionInterface $field */
       foreach ($entity->getFieldDefinitions() as $field) {
         // If this field is reference to taxonomy term.
         if ($field->getType() == 'entity_reference'
@@ -32,7 +35,8 @@ function google_vision_entity_presave(EntityInterface $entity) {
             $vid = reset($field->getSettings()['handler_settings']['target_bundles']);
             google_vision_file_entity_add_labels($entity, $field, $vid);
 
-            // Use a new taxonomy vocabulary to group the objects by their dominant color.
+            // Use a new taxonomy vocabulary to group the objects by their
+            // dominant color.
             $vid = 'dominant_color';
             $vocabulary = Vocabulary::load($vid);
             // Create a vocabulary if not already present.
@@ -157,10 +161,22 @@ function google_vision_form_field_config_form_alt_text_builder($entity_type, Fie
 }
 
 /**
- * Add the terms to the corresponding taxonomy vocabulary and save the
- * values in files.
+ * Add the terms to the corresponding vocabulary and save the values in files.
+ *
+ * @param \Drupal\file\FileInterface $file
+ *   The file entity.
+ * @param \Drupal\Core\Field\FieldDefinitionInterface $field
+ *   The field definition.
+ * @param string $vid
+ *   The vocabulary machine name.
+ * @param array $labels
+ *   An indexed array with the values to be added to the vocabulary. For each
+ *   value received in $labels, this function will use the existing TID if the
+ *   value already exists on the vocabulary, or will create a new term if it is
+ *   new. All TIDs then that correspond to the $labels received will be stored
+ *   into the $file entity passed in.
  */
-function google_vision_add_terms_to_vocabulary($file, $field, $vid, $labels) {
+function google_vision_add_terms_to_vocabulary(FileInterface $file, FieldDefinitionInterface $field, $vid, array $labels) {
   // Get existing values from field.
   $values = $file->get($field->getName())->getValue();
 
@@ -193,7 +209,7 @@ function google_vision_add_terms_to_vocabulary($file, $field, $vid, $labels) {
         ->getStorage('taxonomy_term');
       $label_term = $taxonomy_term_storage->create([
         'name' => $label,
-        'vid' => $vid
+        'vid' => $vid,
       ]);
       $label_term->enforceIsNew();
       $label_term->save();
@@ -206,8 +222,15 @@ function google_vision_add_terms_to_vocabulary($file, $field, $vid, $labels) {
 
 /**
  * Try to get and add labels for the file entity.
+ *
+ * @param \Drupal\file\FileInterface $file
+ *   The file entity.
+ * @param \Drupal\Core\Field\FieldDefinitionInterface $field
+ *   The field definition.
+ * @param string $vid
+ *   The vocabulary machine name.
  */
-function google_vision_file_entity_add_labels($file, $field, $vid) {
+function google_vision_file_entity_add_labels(FileInterface $file, FieldDefinitionInterface $field, $vid) {
   // Try to retrieve file URI.
   $file_uri = $file->getFileUri();
   if ($filepath = \Drupal::service('file_system')->realpath($file_uri)) {
@@ -227,8 +250,15 @@ function google_vision_file_entity_add_labels($file, $field, $vid) {
 
 /**
  * Try to get the dominant color.
+ *
+ * @param \Drupal\file\FileInterface $file
+ *   The file entity.
+ * @param \Drupal\Core\Field\FieldDefinitionInterface $field
+ *   The field definition.
+ * @param string $vid
+ *   The vocabulary machine name.
  */
-function google_vision_file_entity_dominant_color($file, $field, $vid) {
+function google_vision_file_entity_dominant_color(FileInterface $file, FieldDefinitionInterface $field, $vid) {
   $file_uri = $file->getFileUri();
   if ($filepath = \Drupal::service('file_system')->realpath($file_uri)) {
     $data = \Drupal::service('google_vision.api')
@@ -240,21 +270,21 @@ function google_vision_file_entity_dominant_color($file, $field, $vid) {
         $green = $item['color']['green'];
         $blue = $item['color']['blue'];
       }
-      //Create an array of the colors along with their values.
+      // Create an array of the colors along with their values.
       $color = array(
         'red' => $red,
         'green' => $green,
-        'blue' => $blue
+        'blue' => $blue,
       );
       if ($red == $green && $green == $blue) {
         $dominant_color = ['red', 'green', 'blue'];
       }
       else {
         $max_value = max($red, $green, $blue);
-        //Get the dominant color based on the maximum value.
+        // Get the dominant color based on the maximum value.
         $dominant_color = array_keys($color, $max_value);
       }
-      //Add the terms to vocabulary, and set the values to fields in files.
+      // Add the terms to vocabulary, and set the values to fields in files.
       google_vision_add_terms_to_vocabulary($file, $field, $vid, $dominant_color);
     }
   }
@@ -262,15 +292,20 @@ function google_vision_file_entity_dominant_color($file, $field, $vid) {
 
 /**
  * Set the value for the alternative text field of the image file.
+ *
+ * @param \Drupal\file\FileInterface $file
+ *   The file entity.
+ * @param \Drupal\Core\Field\FieldDefinitionInterface $field
+ *   The field definition.
  */
-function google_vision_set_alt_text($entity, $field) {
+function google_vision_set_alt_text(FileInterface $file, FieldDefinitionInterface $field) {
   // Initialize the output.
   $output = '';
   $settings = $field->getThirdPartySettings('google_vision');
   if (!empty($settings['features'])) {
     $option = $settings['features'];
 
-    $file_uri = $entity->getFileUri();
+    $file_uri = $file->getFileUri();
     if ($filepath = \Drupal::service('file_system')->realpath($file_uri)) {
       $gv_service = \Drupal::service('google_vision.api');
       switch ($option) {
@@ -281,6 +316,7 @@ function google_vision_set_alt_text($entity, $field) {
             $output = $data['responses'][0]['labelAnnotations'];
           }
           break;
+
         case 'landmark':
           $data = $gv_service->landmarkDetection($filepath);
           // If we have retrieved landmark.
@@ -311,7 +347,7 @@ function google_vision_set_alt_text($entity, $field) {
     if (!empty($output)) {
       // Grab first value (most relevant) and use it.
       $value = reset($output)['description'];
-      $entity->set('field_image_alt_text', $value);
+      $file->set('field_image_alt_text', $value);
     }
   }
 }