parameters: (self, msg=None)
docstring: Internal: raise a ValueError if file is closed
docstring_summary: Internal: raise a ValueError if file is closed
docstring_tokens: Internal : raise a ValueError if file is closed
function: def _checkClosed(self, msg=None):
          """Internal: raise a ValueError if file is closed
          """
          if self.closed:
              raise ValueError("I/O operation on closed file."
                               if msg is None else msg)
function_tokens: def _checkClosed ( self , msg = None ) : if self . closed : raise ValueError ( "I/O operation on closed file." if msg is None else msg )