title: pytest: are pytest_sessionstart() and pytest_sessionfinish() valid hooks?
body: <p>are <code>pytest_sessionstart(session)</code> and <code>pytest_sessionfinish(session)</code> valid hooks? They are not described in <a href="http://pytest.org/dev/plugins.html" rel="noreferrer">dev hook docs</a> or <a href="http://pytest.org/latest/plugins.html" rel="noreferrer">latest hook docs</a></p>
  
  <p>What is the difference between them and <code>pytest_configure(config)</code>/<code>pytest_unconfigure(config)</code>?</p>
  
  <p>In docs it is said:</p>
  
  <blockquote>
    <p><code>pytest_configure(config)</code>called after command line options have been parsed. and all plugins
    and initial conftest files been loaded.</p>
  </blockquote>
  
  <p>and </p>
  
  <blockquote>
    <p><code>pytest_unconfigure(config)</code> called before test process is exited.</p>
  </blockquote>
  
  <p>Session is the same, right?</p>
  
  <p>Thanks!</p>