Need help with functions

$//$ inserts an element at the end of the list

$//[2]$

void

push$\_$back $($const value$\_$type& value$)$

$\{$

$//$ Hint: could be one$-$line call to insert$()$

ListNode$*$ node $=$ new ListNode$($value$,$ &m$\_$header, m$\_$header.prev$)$;

m$\_$header.prev$->$next $=$ node;

m$\_$header.prev $=$ node;

$++$m$\_$size;

$\}$

$//$ inserts an element at the front of the list

$//[2]$

void

push$\_$front $($const value$\_$type& value$)$

$\{$

$//$ Hint: could be one$-$line call to insert$()$

ListNode$*$ node $=$ new ListNode$($value$,$ m$\_$header.next, &m$\_$header$)$;

m$\_$header.next$->$prev $=$ node;

m$\_$header.next $=$ node;

$++$m$\_$size;

$\}$

$//$ erase element pointed to by "pos" $--$ returns iterator to next element

$//[4]$

iterator

erase $($iterator pos$)$

$\{$

$//$ Hint: call unhook on the correct ListNode and delete it

ListNode$*$ node $=$ pos.m$\_$node;

$++$pos;

node$->$unhook$()$;

delete node;

$--$m$\_$size;

return pos;

$\}$