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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 print_mem(unit="MB"):
 """Show the proc-mem-cost with psutil, use this only for lazinesssss. :param unit: B, KB, MB, GB. """

    try:
        import psutil

        B = float(psutil.Process(os.getpid()).memory_info().vms)
        KB = B / 1024
        MB = KB / 1024
        GB = MB / 1024
        result = vars()[unit]
        print_info("memory usage: %.2f(%s)" % (result, unit))
        return result
    except ImportError:
        print_info("pip install psutil first.")