# File lib/maruku/input/extensions.rb, line 50
        def check_block_extensions(src, con, line)
                BlockExtensions.each do |reg, block|
                        if m = reg.match(line)
                                block = BlockExtensions[reg]
                                accepted =  block.call(doc, src, con)
                                return true if accepted
                        end
                end
                return false # not special
        end