Single leading dash in member variable names?

[e.doxtator at gmail.com]

All

Python noob here.  Trying to understand a particular syntax:

class stuff:
    def __init__(self):
         self._bongo = "BongoWorld"

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What is the significance of the leading underscore in "self._bongo"?  I've seen this a few times and, after looking through PEP 8, I didn't see anything relevant, but I could have missed it.