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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 system_entropy():
 """Return the system's entropy bit count, or -1 if unknown."""

        arg = ['cat', '/proc/sys/kernel/random/entropy_avail']
        proc = Popen(arg, stdout=PIPE, stderr=DEVNULL)
        response = proc.communicate()[0]
        return int(response) if response else -1