parameters: (self, item)
docstring: Put back a checked out item.
          Error if the item is not checked out.
docstring_summary: Put back a checked out item.
          Error if the item is not checked out.
docstring_tokens: Put back a checked out item . Error if the item is not checked out .
function: def checkin(self, item):
          """
          Put back a checked out item.
          Error if the item is not checked out.
          """
          if item not in self.__used:
              self.notify.error("item is not checked out")
          self.__used.remove(item)
          self.__free.append(item)
function_tokens: def checkin ( self , item ) : if item not in self . __used : self . notify . error ( "item is not checked out" ) self . __used . remove ( item ) self . __free . append ( item )