title: Find index span of a sub list from a list
body: <p>Given a list of string L, and a sublist M from L. I want to find an efficient way to find the index span (index_a, index_b) from L where L[index_a: index_b] = M.</p>
  <p>For example,</p>
  <pre><code>L = ['Clement', 'Joseph', 'Man', '##ey', 'was', 'an', 'American', 'businessman', 'from', 'Boston', 'who', 'was', 'president', 'of', 'a', 'contracting', 'company', 'and', 'a', 'minority', 'owner', 'and', 'treasurer', 'of', 'the', 'Boston', 'Braves', 'baseball', 'team', '.']
  M = ['Clement', 'Joseph', 'Man', '##ey']
  
  Expected_result = (0,4) # since L[0:4] = M
  
  L = ['Clement', 'Joseph', 'Man', '##ey', 'was', 'an', 'American', 'businessman', 'from', 'Boston', 'who', 'was', 'president', 'of', 'a', 'contracting', 'company', 'and', 'a', 'minority', 'owner', 'and', 'treasurer', 'of', 'the', 'Boston', 'Braves', 'baseball', 'team', '.']
  M = ['Boston']
  
  Expected_result = (9,9) # both (9,9) and (25,25) are correct since L[9]=L[25]=M
  </code></pre>