Convert all markdown code blocks from indented to the syntax-highlighted ``` blocks

md-hl-code

#!/usr/bin/env ruby

def convert(lang, md)
  md.gsub(/\t/, ' ' * 4).gsub(/((?:^\s{4}[^\n]*\n)+)/) {
    "\n```#{lang}#{$1.gsub(/^[ ]{4}/, '')}```\n"
  }
end

argv = ARGV.dup
path = argv.pop or raise 'pass path'
lang = argv.pop || 'ruby'

puts convert(lang, File.read(path))