<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def from_bytes(cls, data):
 """ I am so sorry. """

        len_username = int.from_bytes(data[0:2], byteorder="big")
        offset_username = 2 + len_username
        username = data[2:offset_username].decode("UTF-8")
        offset_password = 2 + offset_username
        len_password = int.from_bytes(
            data[offset_username:offset_password], byteorder="big"
        )
        pass_begin = offset_password
        pass_end = offset_password + len_password
        password = data[pass_begin:pass_end].decode("UTF-8")

        return cls(username, password)