parameters: (self)
docstring: Raises a ValueError if the underlying file object has been closed.
docstring_summary: Raises a ValueError if the underlying file object has been closed.
docstring_tokens: Raises a ValueError if the underlying file object has been closed .
function: def _check_closed(self):
          """Raises a ValueError if the underlying file object has been closed.
  
          """
          if self.closed:
              raise ValueError('I/O operation on closed file.')
function_tokens: def _check_closed ( self ) : if self . closed : raise ValueError ( 'I/O operation on closed file.' )