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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 diskdata():
 """Get total disk size in GB."""

    p = os.popen("/bin/df -l -P")
    ddata = {}
    tsize = 0
    for line in p.readlines():
        d = line.split()
        if ("/dev/sd" in d[0] or "/dev/hd" in d[0] or "/dev/mapper" in d[0]):
            tsize = tsize + int(d[1])
    ddata["Disk_GB"] = int(tsize)/1000000
    p.close()
    return ddata