<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _load_image(cls, rkey):
 """Load image from file or return the cached instance."""


        v = cls._stock[rkey]
        img = None
        itype = v['type']
        if itype in ('stock', 'data'):
            img = tk.PhotoImage(format=v['format'], data=v['data'])
        elif itype == 'created':
            img = v['image']
        else:
            img = tk.PhotoImage(file=v['filename'])
        cls._cached[rkey] = img
        logger.info('Loaded resource %s.' % rkey)
        return img