How to check duplicate files in django-filer

snippet.py

import hashlib
from filer.models import Image

def check(file: Image, user=None):
  """
  Check duplicate files in django-filer
  """
  sha1 = hashlib.sha1()
  for chunk in file.chunks():
      sha1.update(chunk)
  qs = Image.objects.filter(sha1=sha1.hexdigest())
  if user:
    qs = qs.filter(owner=user)
  dup_im = qs.first()
  if dup_im:
      filer_file = dup_im
  else:
      filer_file = Image.objects.create(
          owner=user,
          is_public=True,
          file=file,
          original_filename=file.name,
          name='whatever',
          folder=folder
      )
  return filer_file