How to calculate the checksum of a ext4 (eg. superblock or inode)

I have an image-file of an ext4 file system (filesystem.img). I am extracting sections sections of the filsystem. Is there a way to manually calculate the the checksum of the sections just with a given byte dump of the section. Given the the superblock according to the documentation the checksum is calculated by using the algorithm CRC32C over the superblock ignoring the checksum field. I have tried to do it in python with the function checksum = crc32c.crc32c(superblock) but with no success yet. Has anybody managed to do this or know what I have to do there? Any help would be appreciated. Thanks