def heartbeat(self, activeSensors):
        if self.output:
            return
        if self.locks[0] and self.locks[1] and self.locks[2]:
            self.output = self.initials[0] + self.initials[1] + self.initials[2]

        r = self.offset[0]
        c = self.offset[1]

        self.display.set(r, c-1, Shapes.charToShape(self.initials[0]), Colors.YELLOW if self.locks[0] else Colors.CYAN)
        self.display.set(r, c, Shapes.charToShape(self.initials[1]), Colors.YELLOW if self.locks[1] else Colors.CYAN)
        self.display.set(r, c+1, Shapes.charToShape(self.initials[2]), Colors.YELLOW if self.locks[2] else Colors.CYAN)