code: def getArrays(self, tree, branchName):
          
          itsArray = self._getArray(tree, branchName)
          if itsArray is None: return None, None
          itsCountArray = self._getCounterArray(tree, branchName)
          return itsArray, itsCountArray
docs: return the array.array objects for the branch and its counter branch
  
          This method returns a pair of the array.array objects. The first one is
          for the given tree and branch name. The second one is for its counter
          branch. The second one will be None when the branch does not have a
          counter. A pair of None will be returned when the tree does not have
          the branch.