title: Windows: Z3Exception("init(Z3_LIBRARY_PATH) must be invoked before using Z3-python")
body: <p>I am running into the following error when using a python script (oyente) that uses Z3 (which I've built in the Visual Studio command prompt):</p>
  
  <pre><code>File "C:\Python27\Lib\site-packages\oyente\z3\z3core.py", line 23, in lib
      raise Z3Exception("init(Z3_LIBRARY_PATH) must be invoked before using Z3-python")
  z3.z3types.Z3Exception: init(Z3_LIBRARY_PATH) must be invoked before using Z3-python
  Exception AttributeError: "Context instance has no attribute 'lib'" in &lt;bound method Context.__del__ of &lt;z3.z3.Context instance at 0x0000000003A5AC48&gt;&gt; ignored
  </code></pre>
  
  <p>I have the <code>libz3.dll</code> file in the z3 and oyente directory, and in my PYTHONPATH in system variables I have added every directory that might possibly need to be there, eg:</p>
  
  <p><a href="https://i.stack.imgur.com/9gw59.png" rel="noreferrer"><img src="https://i.stack.imgur.com/9gw59.png" alt="enter image description here"></a></p>