title: Custom filetype in Python 3
body: <p>How to start creating my own filetype in Python ? I have a design in mind but how to pack my data into a file with a specific format ?</p>
  
  <p>For example I would like my fileformat to be a mix of an archive ( like other format such as zip, apk, jar, etc etc, they are basically all archives ) with some room for packed files, plus a section of the file containing settings and serialized data that will not be accessed by an archive-manager application.</p>
  
  <p>My requirement for this is about doing all this with the default modules for Cpython, without external modules.</p>
  
  <p>I know that this can be long to explain and do, but I can't see how to start this in Python 3.x with Cpython. </p>