・When it's 1, PRGGET is called and the current line is acquired and automatically moved down one line. As a result, the source code can be acquired line by line by simply calling PRGGET.
・When it's 0, the current line is not moved automatically. The current line must be moved with PRGSEEK.
・If not specified, 1 is specified.
・The source string of the current line (empty string if out of range)
A$=PRGGET$()