multiline "it" declaration

Example of using rewritable "it" blocks:
{{##def.defBlock
  This block you can't override using the same name.
#}}
{{-it.block:
  <h1>Block1</h1>
  <div class="block-div">
    {{!it.foo}}<br>
    {{#def.defBlock}}
  </div>
-}}
{{=it.block}}
{{-it.block:
  <h1>Block2</h1>
  <div class="block-div">
    {{!it.foo}}<br>
    {{#def.defBlock}}
  </div>
-}}
{{=it.block}}