diff --git a/app/src/main/java/ua/acclorite/book_story/data/local/data_store/DataStore.kt b/app/src/main/java/ua/acclorite/book_story/data/local/data_store/DataStore.kt
index 83153c59..a40e2513 100644
--- a/app/src/main/java/ua/acclorite/book_story/data/local/data_store/DataStore.kt
+++ b/app/src/main/java/ua/acclorite/book_story/data/local/data_store/DataStore.kt
@@ -1,10 +1,8 @@
 package ua.acclorite.book_story.data.local.data_store
 
 import androidx.datastore.preferences.core.Preferences
-import kotlinx.coroutines.flow.Flow
 
 interface DataStore {
-    suspend fun <T> getData(key: Preferences.Key<T>, defaultValue: T): Flow<T>
     suspend fun <T> getNullableData(key: Preferences.Key<T>): T?
     suspend fun getAllData(): Set<Preferences.Key<*>>?
     suspend fun <T> putData(key: Preferences.Key<T>, value: T)
diff --git a/app/src/main/java/ua/acclorite/book_story/data/local/data_store/DataStoreImpl.kt b/app/src/main/java/ua/acclorite/book_story/data/local/data_store/DataStoreImpl.kt
index 53599a1f..09eaaf2d 100644
--- a/app/src/main/java/ua/acclorite/book_story/data/local/data_store/DataStoreImpl.kt
+++ b/app/src/main/java/ua/acclorite/book_story/data/local/data_store/DataStoreImpl.kt
@@ -6,7 +6,6 @@ import androidx.datastore.preferences.core.Preferences
 import androidx.datastore.preferences.core.edit
 import androidx.datastore.preferences.core.emptyPreferences
 import androidx.datastore.preferences.preferencesDataStore
-import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.firstOrNull
 import kotlinx.coroutines.flow.map
@@ -18,38 +17,30 @@ private val Context.dataStore by preferencesDataStore("data_store")
 class DataStoreImpl @Inject constructor(context: Application) : DataStore {
     private val dataStore = context.dataStore
 
-    override suspend fun <T> getData(key: Preferences.Key<T>, defaultValue: T): Flow<T> =
-        dataStore.data.catch { exception ->
-            if (exception is IOException) {
-                emit(emptyPreferences())
-            } else {
-                throw exception
-            }
-        }.map { preferences ->
-            val result = preferences[key] ?: defaultValue
-            result
-        }
-
+    /**
+     * Gets data from DataStore by given [key]. If no such [key] exists, returns null.
+     */
     override suspend fun <T> getNullableData(key: Preferences.Key<T>): T? =
         dataStore.data.catch { exception ->
-            if (exception is IOException) {
-                emit(emptyPreferences())
-            } else {
-                throw exception
-            }
+            if (exception is IOException) emit(emptyPreferences())
+            else throw exception
         }.map { preferences ->
-            val result = preferences[key]
-            result
+            preferences[key]
         }.firstOrNull()
 
+    /**
+     * Gets all keys from DataStore.
+     */
     override suspend fun getAllData(): Set<Preferences.Key<*>>? {
-        val keys = dataStore.data
+        return dataStore.data
             .map {
                 it.asMap().keys
-            }
-        return keys.firstOrNull()
+            }.firstOrNull()
     }
 
+    /**
+     * Puts data in DataStore by given [key].
+     */
     override suspend fun <T> putData(key: Preferences.Key<T>, value: T) {
         dataStore.edit { preferences ->
             preferences[key] = value
diff --git a/app/src/main/java/ua/acclorite/book_story/data/local/notification/UpdatesNotificationServiceImpl.kt b/app/src/main/java/ua/acclorite/book_story/data/local/notification/UpdatesNotificationServiceImpl.kt
index 764c969b..40420722 100644
--- a/app/src/main/java/ua/acclorite/book_story/data/local/notification/UpdatesNotificationServiceImpl.kt
+++ b/app/src/main/java/ua/acclorite/book_story/data/local/notification/UpdatesNotificationServiceImpl.kt
@@ -20,6 +20,11 @@ class UpdatesNotificationServiceImpl @Inject constructor(
     private val notificationManager = application.getSystemService(Context.NOTIFICATION_SERVICE)
             as NotificationManager
 
+    /**
+     * Sends notification about new update.
+     *
+     * @param releaseInfo [LatestReleaseInfo].
+     */
     override fun postNotification(releaseInfo: LatestReleaseInfo) {
         val downloadLatestVersionIntent = Intent(
             Intent.ACTION_VIEW,
diff --git a/app/src/main/java/ua/acclorite/book_story/data/local/room/BookDao.kt b/app/src/main/java/ua/acclorite/book_story/data/local/room/BookDao.kt
index 8506210a..5ef972fc 100644
--- a/app/src/main/java/ua/acclorite/book_story/data/local/room/BookDao.kt
+++ b/app/src/main/java/ua/acclorite/book_story/data/local/room/BookDao.kt
@@ -12,9 +12,13 @@ import ua.acclorite.book_story.data.local.dto.ColorPresetEntity
 import ua.acclorite.book_story.data.local.dto.FavoriteDirectoryEntity
 import ua.acclorite.book_story.data.local.dto.HistoryEntity
 
+/**
+ * Class to manipulate Room database.
+ */
 @Dao
 interface BookDao {
 
+    /* ------ BookEntity ------------------------ */
     @Insert(onConflict = OnConflictStrategy.REPLACE)
     suspend fun insertBooks(
         books: List<BookEntity>
@@ -39,8 +43,10 @@ interface BookDao {
 
     @Update
     suspend fun updateBooks(books: List<BookEntity>)
+    /* - - - - - - - - - - - - - - - - - - - - - - */
 
 
+    /* ------ HistoryEntity --------------------- */
     @Query("SELECT * FROM historyentity")
     suspend fun getHistory(): List<HistoryEntity>
 
@@ -60,8 +66,10 @@ interface BookDao {
 
     @Delete
     suspend fun deleteHistory(history: List<HistoryEntity>)
+    /* - - - - - - - - - - - - - - - - - - - - - - */
 
 
+    /* ------ ColorPresetEntity ----------------- */
     @Upsert
     suspend fun updateColorPreset(colorPreset: ColorPresetEntity)
 
@@ -79,8 +87,10 @@ interface BookDao {
 
     @Query("DELETE FROM colorpresetentity")
     suspend fun deleteColorPresets()
+    /* - - - - - - - - - - - - - - - - - - - - - - */
 
 
+    /* ------ FavoriteDirectoryEntity ----------- */
     @Upsert
     suspend fun insertFavoriteDirectory(favoriteDirectoryEntity: FavoriteDirectoryEntity)
 
@@ -89,4 +99,5 @@ interface BookDao {
 
     @Delete
     suspend fun deleteFavoriteDirectory(favoriteDirectoryEntity: FavoriteDirectoryEntity)
+    /* - - - - - - - - - - - - - - - - - - - - - - */
 }
\ No newline at end of file
diff --git a/app/src/main/java/ua/acclorite/book_story/data/mapper/color_preset/ColorPresetMapperImpl.kt b/app/src/main/java/ua/acclorite/book_story/data/mapper/color_preset/ColorPresetMapperImpl.kt
index d11cbded..86a6e12a 100644
--- a/app/src/main/java/ua/acclorite/book_story/data/mapper/color_preset/ColorPresetMapperImpl.kt
+++ b/app/src/main/java/ua/acclorite/book_story/data/mapper/color_preset/ColorPresetMapperImpl.kt
@@ -6,7 +6,6 @@ import ua.acclorite.book_story.domain.model.ColorPreset
 import javax.inject.Inject
 
 class ColorPresetMapperImpl @Inject constructor() : ColorPresetMapper {
-
     override suspend fun toColorPresetEntity(
         colorPreset: ColorPreset,
         order: Int
diff --git a/app/src/main/java/ua/acclorite/book_story/data/repository/BookRepositoryImpl.kt b/app/src/main/java/ua/acclorite/book_story/data/repository/BookRepositoryImpl.kt
index b958ca04..78a33bc8 100644
--- a/app/src/main/java/ua/acclorite/book_story/data/repository/BookRepositoryImpl.kt
+++ b/app/src/main/java/ua/acclorite/book_story/data/repository/BookRepositoryImpl.kt
@@ -429,13 +429,6 @@ class BookRepositoryImpl @Inject constructor(
         return true
     }
 
-    override suspend fun <T> retrieveDataFromDataStore(
-        key: Preferences.Key<T>,
-        defaultValue: T
-    ): Flow<T> {
-        return dataStore.getData(key, defaultValue)
-    }
-
     override suspend fun <T> putDataToDataStore(key: Preferences.Key<T>, value: T) {
         dataStore.putData(key, value)
     }
diff --git a/app/src/main/java/ua/acclorite/book_story/domain/repository/BookRepository.kt b/app/src/main/java/ua/acclorite/book_story/domain/repository/BookRepository.kt
index a0c6669e..b4d99b1b 100644
--- a/app/src/main/java/ua/acclorite/book_story/domain/repository/BookRepository.kt
+++ b/app/src/main/java/ua/acclorite/book_story/domain/repository/BookRepository.kt
@@ -58,12 +58,6 @@ interface BookRepository {
 
     suspend fun resetCoverImage(bookId: Int): Boolean
 
-
-    suspend fun <T> retrieveDataFromDataStore(
-        key: Preferences.Key<T>,
-        defaultValue: T
-    ): Flow<T>
-
     suspend fun <T> putDataToDataStore(
         key: Preferences.Key<T>,
         value: T
diff --git a/app/src/main/java/ua/acclorite/book_story/domain/use_case/GetDatastore.kt b/app/src/main/java/ua/acclorite/book_story/domain/use_case/GetDatastore.kt
deleted file mode 100644
index f6581105..00000000
--- a/app/src/main/java/ua/acclorite/book_story/domain/use_case/GetDatastore.kt
+++ /dev/null
@@ -1,13 +0,0 @@
-package ua.acclorite.book_story.domain.use_case
-
-import androidx.datastore.preferences.core.Preferences
-import kotlinx.coroutines.flow.Flow
-import ua.acclorite.book_story.domain.repository.BookRepository
-import javax.inject.Inject
-
-class GetDatastore @Inject constructor(private val repository: BookRepository) {
-
-    suspend fun <T> execute(key: Preferences.Key<T>, defaultValue: T): Flow<T> {
-        return repository.retrieveDataFromDataStore(key, defaultValue)
-    }
-}
\ No newline at end of file