title: result when __all__ is not defined in __init__.py of package?
body: <p>I am just learning and practicing python,on the way,i am reading about python packages and how to import into other modules or package at <a href="https://docs.python.org/3/tutorial/modules.html" rel="nofollow">Modules</a> ,I assume the following scenario ,</p>
  
  <p>I have package as ,</p>
  
  <pre><code>Video/
      __init__.py
      formats/
          __init__.py 
          mkv.py  
          mp4.py
      length/
          __init__.py
          morethan20min.py
          lessthan20min.py
  </code></pre>
  
  <p>and in no </p>
  
  <pre><code>__init__.py
  </code></pre>
  
  <p>I have not defined</p>
  
  <pre><code>__all__
  </code></pre>
  
  <p>what happens if i have an import statement as,</p>
  
  <pre><code>import Video.format.mkv
  import Video.formats.* 
  </code></pre>
  
  <p>Since I have already imported mkv module in first statement,what exactly happens after execution of second import statement,I didnt get the concept after reading on the mentioned link.</p>