code: def get_vg(self, name, mode="r"):
          
          vg = VolumeGroup(self, name=name, mode=mode)
          return vg
docs: Returns an instance of VolumeGroup. The name parameter should be an existing
          volume group. By default, all volume groups are open in "read" mode::
  
              from lvm2py import *
  
              lvm = LVM()
              vg = lvm.get_vg("myvg")
  
          To open a volume group with write permissions set the mode parameter to "w"::
  
              from lvm2py import *
  
              lvm = LVM()
              vg = lvm.get_vg("myvg", "w")
  
          *Args:*
  
          *       name (str):     An existing volume group name.
          *       mode (str):     "r" or "w" for read/write respectively. Default is "r".
  
          *Raises:*
  
          *       HandleError