recursive parsing test.
you can parse entire blocks+subblocks using rparse().
note: this will parse every subblock recursively inside the block you specified.
here comes the test [ rparse("main") ]: ===>
this is block 1.
this is subblock 1.1
this is block 1.2
this is block 2.
this is subblock 2.1
this is block 2.2
this is block 3.