'Return the category of this SimMemory instance. It can be one of the three following categories: reg, mem,
or file.'

@property
def category(self):

    if (self.id in ('reg', 'mem')):
        return self.id
    elif self._abstract_backer:
        return 'mem'
    elif self.id.startswith('file'):
        return 'file'
    else:
        raise SimMemoryError(('Unknown    SimMemory    category    for    memory_id    "%s"' % self.id))
