title: pip install -- python 3 -- conda [Illegal instruction: 4]
body: <p>i'm doing pip install of <code>scikit-learn</code> and <code>nltk</code> in python 3.6 and get error Illegal instruction: 4. i'm on osx 10.7.5. i had earlier updated python 3 version with conda install python=3</p>
  
  <p>i've re-installed conda, and it looks like a complier error. i'm not fully sure how to de-bug it. </p>
  
  <p>how can i understand what's causing this error? 
  how can i fix this? </p>