title: Python: How to iterate through two iterators simultaneously in a single loop? (Each iterator also has two yield outputs)
body: <p>I have two iterators (A_subseq and B_subseq), and each iterator has two yield outputs (Aseq and Ahseq from A_subseq).  I need to keep index count of both iterators.  This can be done if I can combine the two for loops into a single loop.</p>
  
  <p>Both a and b are iterators.  k is just a constant integer.</p>
  
  <pre><code>a_count = 0
  b_count = 0
  
  A_subseq = subsequenceHashes(a,k)
  B_subseq = subsequenceHashes(b,k)
  
  Match = Multidict()
  
  for Aseq,Ahash in A_subseq:
      Match.put(Ahash,Aseq)
  
  for Bseq,Bhash in B_subseq:
      b_count += 1
      if Bseq in Match.get(Bhash):
          yield xxx
  </code></pre>
  
  <p>Does anyone know if I can combine these two for loops so that I can keep count of both a_count and b_count?</p>