<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def matchBytes(self, bytes):
 """Look for a sequence of bytes at the start of a string. If the bytes are found return True and advance the position to the byte after the match. Otherwise return False and leave the position alone"""

        p = self.position
        data = self[p:p + len(bytes)]
        rv = data.startswith(bytes)
        if rv:
            self.position += len(bytes)
        return rv