code: def filter_instance(inst, plist):
      
  
      if plist is not None:
          for pname in inst.properties.keys():
              if pname.lower() not in plist:
                  del inst.properties[pname]
docs: Remove properties from an instance that aren't in the PropertyList
  
      inst -- The CIMInstance
      plist -- The property List, or None.  The list items must be all
          lowercase.