What does `import _preamble` do in Python?
Question: I notice the following at the top of Twisted's `twistd.py` script:

    
    
    import os, sys
    
    try:
        import _preamble
    except ImportError:
        sys.exc_clear()
    
    sys.path.insert(0, os.path.abspath(os.getcwd()))
    

What does `import _preamble` do? I can't seem to find any references to it on
the google-mage.


Answer: `_preamble` is a module like any other. In twisted's case, this is simply [the
module](http://twistedmatrix.com/trac/browser/trunk/bin/_preamble.py) that
sets up [`sys.path`](http://docs.python.org/3/library/sys.html#sys.path) so
that you can run twisted in development setups.

