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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 _GetMountpoints(only_physical=True):
 """Fetches a list of mountpoints. Args: only_physical: Determines whether only mountpoints for physical devices (e.g. hard disks) should be listed. If false, mountpoints for things such as memory partitions or `/dev/shm` will be returned as well. Returns: A set of mountpoints. """

  partitions = psutil.disk_partitions(all=not only_physical)
  return set(partition.mountpoint for partition in partitions)