title: Convert string to actual UTF-8 character
body: <p>the sample file contains this.
  <code>[&amp;quot; \u042D\u0440\u044B\u0433\u044D\u0436\u044D\u044D. \n&amp;quot;]</code></p>
  
  <p>I want to replace <code>\u[a-zA-Z0-9]</code> chars with actual utf-8 character.
  What should be done?</p>
  
  <pre><code>File.new("mnosis.xml").each_line do |line|
    re = /\\u[0-9a-fA-F]{4}/
    new_str = line.gsub(re) {|match| puts match[0..1] + '#{' + match[2..5] + '}' }
    puts new_str
  end
  </code></pre>