EDIT—INPUT subcommand syntax

                                              .-I-.   
>>-+-INPUT-+--+----------------------------+--+---+------------->
   '-I-----'  +-*--------------------------+  '-R-'   
              '-line_number--+-----------+-'          
                             '-increment-'            

>--+----------+------------------------------------------------><
   +-PROMPT---+   
   '-NOPROMPT-'