<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def can_mark_block_complete_on_view(self, block):
 """ Returns True if the xblock can be marked complete on view. This is true of any non-customized, non-scorable, completable block. """

        return (
            XBlockCompletionMode.get_mode(block) == XBlockCompletionMode.COMPLETABLE
            and not getattr(block, 'has_custom_completion', False)
            and not getattr(block, 'has_score', False)
        )