<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_byte(self, index):
 """ Extracts a byte from a BV, where the index refers to the byte in a big-endian order :param index: the byte to extract :return: An 8-bit BV """

        pos = self.size() // 8 - 1 - index
        return self[pos * 8 + 7 : pos * 8]