title: Binary string comparison
body: <p>I'm just learning python and the best way to learn a language is to use it, so I thought I'd make a script that compares binary words to determine which ones are grey. </p>
  
  <p>If there is one bit that is different then it should flag record which number binary code it is. So by means of example, if N=3 then the binary code is 000, 001, 010, 011, 100, 101, 110, 111 </p>
  
  <p>If I chose my first binary code as 010 then the code should return 110, 000, 011 as the results, or preferably the indices 0,3,6 (or 1,4,7).</p>
  
  <p>My question is this : </p>
  
  <p>What is the best pythonic way to do this, mostly I'm aiming at the fastest code. </p>
  
  <p>My reason is that some of you would have a better idea on the optimal way to do this and I could then compare my code to that and this would teach me far more.</p>