title: How to import one submodule from different submodule?
body: <p>My project has the following structure:</p>
  
  <pre><code>DSTC/
      st/
          __init__.py
          a.py
          g.py
          tb.py
      dstc.py
  </code></pre>
  
  <p>Here is <code>a.py</code> in part:</p>
  
  <pre><code>import inspect
  import queue
  import threading
  </code></pre>
  
  <p>Here is <code>tb.py</code> in part:</p>
  
  <pre><code>import functools
  from . import a
  </code></pre>
  
  <p>When run directly, <code>a.py</code> produces no errors, and it is easy to verify there were no <code>SyntaxError</code>s. However, running <code>tb.py</code> causes the following error:</p>
  
  <pre><code>"C:\Program Files\Python36\python.exe" C:/Users/user/PycharmProjects/DSTC/st/tb.py
  Traceback (most recent call last):
    File "C:/Users/user/PycharmProjects/DSTC/st/tb.py", line 15, in &lt;module&gt;
      from . import a
  ImportError: cannot import name 'a'
  
  Process finished with exit code 1
  </code></pre>
  
  <p>How should I rewrite the import of <code>a</code> from <code>tb</code> so that <code>tb</code> can be run directly without causing errors?</p>