class Tester(db.Document):
     image = ImageField(fs=storage, max_size=100, optimize=True)
 class Tester(db.Document):
     image = ImageField(fs=storage,
                        basename=lambda o: 'prefix/filename')
 class Tester(db.Document):
     image = ImageField(fs=storage, upload_to=lambda o: upload_to)
 class Tester(db.Document):
     image = ImageField(fs=storage, max_size=max_size)
 class Tester(db.Document):
     image = ImageField(fs=storage, thumbnails=sizes)
     image2 = ImageField(fs=storage)
 class Tester(db.Document):
     image = ImageField(fs=storage)