When you're not doing send previews, big AMPscript code blocks can make your email un-readable. You can easily hide a block using the following :
<!== ==>But if you save this one into a free form this might transform it but still hide the code.
You can also do the following
%%[
/* My ampscript comment that describes the block <div style="display:none"> */
here goes the code
/*</div>*/
]%%