Function            vert_line - draw a vertical line

  Syntax              void vert_line(byte c, int len, int col, int row);

  Prototype in        video.h

  Remarks             draws a vertical line of characters c of length len
                      beginning at (col,row) via INTerrupts, using the
                      current char_attribute setting for color. Screen
                      coordinates are absolute.

                      horiz_line does no error checking on the passed
                      parameters.

  Return value        nothing.

  See also            box(), horiz_line(), restore_box(),
                      restore_screen(), save_box(), save_screen()

  Example             #include <video.h>

                      main()
                      {
                           vert_line('*',7,4,4);    /* draw 7 *'s */
                      }