title: PyYAML and unusual tags
body: <p>I am working on a project that uses the Unity3D game engine.  For some of the pipeline requirements, it is best to be able to update some files from external tools using Python.  Unity's meta and anim files are in YAML so I thought this would be strait forward enough using PyYAML.</p>
  
  <p>The problem is that Unity's format uses custom attributes and I am not sure how to work with them as all the examples show more common tags used by Python and Ruby.</p>
  
  <p>Here is what the top lines of a file look like:</p>
  
  <pre><code>%YAML 1.1
  %TAG !u! tag:unity3d.com,2011:
  --- !u!74 &amp;7400000
  AnimationClip:
    m_ObjectHideFlags: 0
    m_PrefabParentObject: {fileID: 0}
    ...
  </code></pre>
  
  <p>When I try to read the file I get this error:</p>
  
  <pre><code>could not determine a constructor for the tag 'tag:unity3d.com,2011:74'
  </code></pre>
  
  <p>Now after looking at all the other questions asked, this tag scheme does not seem to resemble those questions and answers.  For example this file uses "!u!" which I was unable to figure out what it means or how something similar would behave (my wild uneducated guess says it looks like an alias or namespace).</p>
  
  <p>I can do a hack way and strip the tags out but that is not the ideal way to try to do this.  I am looking for help on a solution that will properly handle the tags and allow me to parse &amp; encode the data in a way that preserves the proper format.</p>
  
  <p>Thanks,
  -R</p>