Related Syntax
operator	is closed

Return type: Boolean
Returns:       

True if the stream is closed, false otherwise. Replacing is with isnt will reverse the results.

  stream-name indexer? (is | isnt) closed

One type of stream test to check for the state of a stream to determine whether it is closed.

A stream is closed if the stream has been opened or reopened, and is now closed.

A stream must be closed to be used in a "%g" format item or in a string expression.