title: How to start from second index for for-loop
body: <p>I have this for-loop. I want <code>i in range(nI)</code> to start from the second number in the <code>I</code> list. Could you guide me?</p>
  
  <pre><code>I=[0,1,2,3,4,5,6]
  nI=len(I)
  for i in range(nI):
      sum=0
      for v in range(nV):
          for j in range(nJ):
              sum=sum+x1[i][j][v]
  return sum
  </code></pre>