Missing :endfunction error for vim function -

in vimrc file trying write function take in 2 lines numbers arguments , comments out lines in range. using substitute start of line '^' , replacing '#' works fine when call outside function. function have far:

function comment(line1, line2) a:line1,a:line2s/^/#/g endfunction

this not working though , getting error when try start vim saying 'missing :endfunction'

in command:

a:line1,a:line2s/^/#/g 

some parts variables (a:line1 , a:line2). need evaluated. so, can wrap every part of command inside string, except variables, concatenate parts dot operator, , pass result command :execute execute regular ex command:

execute a:line1.','.a:line2.'s/^/#/g' 

if need command call it, try one:

function! comment(line1, line2)     execute a:line1.','.a:line2.'s/^/#/' endfunction  command! -range=% comment call comment(<line1>,<line2>) 

it defines :comment command calls function same name. accepts range, because it's defined -range attribute. if don't provide range command, use whole buffer, because % (=1,$) defined default range. see :h user-commands more info.

to use command, visually select lines, execute:

:'<,'>comment 

to use function, assuming wanted comment lines address between 10 , 20, execute:

:call comment(10,20) 

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it's not linked issue, if don't add bang keyword function, every time source script, you'll have error:

e122: function comment exists, add ! replace 

same thing command, want add bang after keyword command, otherwise you'll have error:

e174: command exists: add ! replace