docs: def __get_datadir(self, app=False):
          """
          Draw a dialog for directory selection.
          """
          # if 'datadir' in self.oseg.cache.data.keys():
          # if :
          #     directory = self.oseg.input_datapath_start
          if self.cache is not None:
              cache_loaddir = self.cache.get_or_none('loaddir')
              self.loaddir = str(cache_loaddir)
              # self.loaddir = str(self.cache.get_or_none('loaddir'))
  
          if self.loaddir is None:
              self.loaddir = ''
  
          directory = self.loaddir
  
          from PyQt4.QtGui import QFileDialog
          if not app:
              app_inner = QApplication(sys.argv)
          if self._skip_get_path_dialog_for_tests:
              dcmdir = self.datapath
          else:
              dcmdir = QFileDialog.getExistingDirectory(
                  caption='Select DICOM Folder',
                  options=QFileDialog.ShowDirsOnly,
                  directory=directory
              )
              # pp.exec_()
          if not app:
              app_inner.exit(0)
  
          dcmdir = get_str(dcmdir)
  
          if len(dcmdir) > 0:
  
  
              # dcmdir = "%s" % (dcmdir)
              # dcmdir = dcmdir.encode("utf8")
              pass
          else:
              dcmdir = None
  
          if self.cache is not None:
              self.cache.update('loaddir', dcmdir)
          return str(dcmdir)