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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def submissionfile_post_save(sender, instance, signal, created, **kwargs):
    '''
        Update MD5 field for newly uploaded files.
    '''
    if created:
        logger.debug("Running post-processing for new submission file.")
        instance.md5 = instance.attachment_md5()
        instance.save()