<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def copy_signal(signal_glob, source_db, target_db):
 # type: (str, cm.CanMatrix, cm.CanMatrix) -> None """ Copy Signals identified by name from source CAN matrix to target CAN matrix. In target CanMatrix the signal is put without frame, just on top level. :param signal_glob: Signal glob pattern :param source_db: Source CAN matrix :param target_db: Destination CAN matrix """

    for frame in source_db.frames:
        for signal in frame.glob_signals(signal_glob):
            target_db.add_signal(signal)