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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 rssi_bars(self) -> int: """Received Signal Strength Indication, from 0 to 4 bars."""

        rssi_db = self.rssi_db
        if rssi_db < 45:
            return 0
        elif rssi_db < 60:
            return 1
        elif rssi_db < 75:
            return 2
        elif rssi_db < 90:
            return 3
        return 4