parameters: (self, msg=None)
docstring: Internal: raise an IOError if file is not writable
docstring_summary: Internal: raise an IOError if file is not writable
docstring_tokens: Internal : raise an IOError if file is not writable
function: def _checkWritable(self, msg=None):
          """Internal: raise an IOError if file is not writable
          """
          if not self.writable():
              raise IOError("File or stream is not writable."
                            if msg is None else msg)
function_tokens: def _checkWritable ( self , msg = None ) : if not self . writable ( ) : raise IOError ( "File or stream is not writable." if msg is None else msg )