Sends a line of input back to the running application, followed by a </n> newline character.
When one more more values are pushed into the tag's default field, they are sent as standard input back to the running program.
When the putLn tag is complete, a new-line character is added to the end of the running program's input and the tag's lifetime then ends.
The putLn tag does not produce a value. No result value is yielded back into the document tree.