deletions | additions       diff --git a/Lecture_7_Externalities_this_is__.md b/Lecture_7_Externalities_this_is__.md  index aba8b07..de9b76a 100644  --- a/Lecture_7_Externalities_this_is__.md  +++ b/Lecture_7_Externalities_this_is__.md 
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Positive externalities! Like when you hear a beautiful singer rehearsing. (Not referring to a brand of sewing machine)  Oh oh quick we're on to electricity markets already. 
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