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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def wait_for_boot_completion( self, timeout=DEFAULT_TIMEOUT_BOOT_COMPLETION_SECOND):
 """Waits for Android framework to broadcast ACTION_BOOT_COMPLETED. This function times out after 15 minutes. Args: timeout: float, the number of seconds to wait before timing out. If not specified, no timeout takes effect. """

        timeout_start = time.time()

        self.adb.wait_for_device(timeout=timeout)
        while time.time() < timeout_start + timeout:
            try:
                if self.is_boot_completed():
                    return
            except adb.AdbError:
                # adb shell calls may fail during certain period of booting
                # process, which is normal. Ignoring these errors.
                pass
            time.sleep(5)
        raise DeviceError(self, 'Booting process timed out')