<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def unpack(self, unpacker):
 """ Unpack an attributes table from an unpacker stream. Modifies the structure of this instance. """


        # bound method for dereferencing constants
        cval = self.cpool.deref_const

        (count,) = unpacker.unpack_struct(_H)
        for _i in range(0, count):
            (name, size) = unpacker.unpack_struct(_HI)
            self[cval(name)] = unpacker.read(size)