docs: def get_subscript(self, sub_script_name):
          """
          finds the item that contains the sub_script with name sub_script_name
          Args:
              sub_script_name: name of subscript
          Returns: B26QTreeItem in QTreeWidget which is a script
  
          """
  
          # get tree of item
          tree = self.treeWidget()
  
          items = tree.findItems(sub_script_name, QtCore.Qt.MatchExactly | QtCore.Qt.MatchRecursive)
  
          if len(items) >= 1:
              # identify correct script by checking that it is a sub_element of the current script
              subscript_item = [sub_item for sub_item in items if isinstance(sub_item.value, Script)
                                 and sub_item.parent() is self]
  
              subscript_item = subscript_item[0]
          else:
              raise ValueError('several elements with name ' + sub_script_name)
  
  
          return subscript_item