Return a custom class for sized InputFile instead extra attrs

telethon/tl/custom/__init__.py

@@ -1,2 +1,3 @@
 from .draft import Draft
 from .dialog import Dialog
+from .input_sized_file import InputSizedFile

telethon/tl/custom/input_sized_file.py

@@ -0,0 +1,9 @@
+from ..types import InputFile
+
+
+class InputSizedFile(InputFile):
+    """InputFile class with two extra parameters: md5 (digest) and size"""
+    def __init__(self, id_, parts, name, md5, size):
+        super().__init__(id_, parts, name, md5.hexdigest())
+        self.md5 = md5.digest()
+        self.size = size