sub foo { $_[0]+$_[1] }
my $template=<<END;
This is some line.
This is a line with some expression: # $foo(3,5) #
# foreach my $s qw(this that) { #
This is # $s # line
# } #
This is the end
END

##</code><code>##

This is some line.
This is a line with some expression: 8
This is this line
This is that line
This is the end