Python: Underscore In Front of Variable

"In addition, the following special forms using leading or trailing underscores are recognized (these can generally be combined with any case convention): _single_leading_underscore: weak "internal use" indicator. E.g. "from M import *" does not import objects whose name starts with an underscore."


source: http://stackoverflow.com/questions/6700826/in-python-what-is-the-underscore-in-front-of-the-instance-variable