diff --git a/backend/app/utils/file_utils.py b/backend/app/utils/file_utils.py
index 20119171..006080f0 100644
--- a/backend/app/utils/file_utils.py
+++ b/backend/app/utils/file_utils.py
@@ -1,19 +1,20 @@
 import base64
 import mimetypes
 from pathlib import Path
-from typing import Optional
+
 
 def encode_file_to_base64_data_url(file_path: str) -> str:
     """
     Read a file and encode it as a base64 data URL with the appropriate MIME type.
     """
     path = Path(file_path)
-    mime_type = mimetypes.guess_type(path)[0] or 'application/octet-stream'
+    mime_type = mimetypes.guess_type(path)[0] or "application/octet-stream"
 
-    with open(path, 'rb') as f:
+    with open(path, "rb") as f:
         file_content = f.read()
-        base64_data = base64.b64encode(file_content).decode('utf-8')
-        return f'data:{mime_type};base64,{base64_data}'
+        base64_data = base64.b64encode(file_content).decode("utf-8")
+        return f"data:{mime_type};base64,{base64_data}"
+
 
 def get_file_mime_type(file_path: str) -> str:
     """
@@ -24,14 +25,14 @@ def get_file_mime_type(file_path: str) -> str:
         # Default MIME types for common file types
         ext = Path(file_path).suffix.lower()
         mime_map = {
-            '.pdf': 'application/pdf',
-            '.txt': 'text/plain',
-            '.jpg': 'image/jpeg',
-            '.jpeg': 'image/jpeg',
-            '.png': 'image/png',
-            '.gif': 'image/gif',
-            '.mp3': 'audio/mpeg',
-            '.mp4': 'video/mp4',
+            ".pdf": "application/pdf",
+            ".txt": "text/plain",
+            ".jpg": "image/jpeg",
+            ".jpeg": "image/jpeg",
+            ".png": "image/png",
+            ".gif": "image/gif",
+            ".mp3": "audio/mpeg",
+            ".mp4": "video/mp4",
         }
-        mime_type = mime_map.get(ext, 'application/octet-stream')
-    return mime_type
\ No newline at end of file
+        mime_type = mime_map.get(ext, "application/octet-stream")
+    return mime_type