Write code to fill in $/*$ missing code $1*/,/*$ missing code $2*/,$ and $/*$ missing code $3*/$ to complete the decoder function so that it returns the string message decoded according to the following rules:

$-$ First, remove every $$x$$

$-$ Next, remove every third letter

For example, the function call decoder$($HxaeppqxxyHxaolixidrxayvs$)$ would return $$HappyHolidays$.$