'Simple implementation of overwriting any existing xblock'

def import_xblock(self, user_id, course_key, block_type, block_id, fields=None, runtime=None, **kwargs):

    if (block_type == 'course'):
        block_id = course_key.run
    xblock = self.create_xblock(runtime, course_key, block_type, block_id, fields)
    return self.update_item(xblock, user_id, allow_not_found=True)
