<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _write4bits(self, value):
 """Write 4 bits of data into the data bus."""

        for i in range(4):
            bit = (value >> i) & 0x01
            GPIO.output(self.pins[i + 7], bit)
        self._pulse_enable()