title: erlang list filter question
body: <p>I have list - Sep1:</p>
  
  <pre><code>[
     ....
     ["Message-ID", "AAAAAAAAAAAAAAAAAAA"],
     ["To", "BBBBBBBBBBBBBBBBB"]
     ...
  ]
  </code></pre>
  
  <p>I try get element where first item = Message_ID for example:</p>
  
  <pre><code>lists:filter(fun(Y) -&gt; (lists:nth(1,lists:nth(1,Y)) =:= "Message-ID") end, Sep1).
  </code></pre>
  
  <p>But i get error:</p>
  
  <pre><code> exception error: no function clause matching lists:nth(1,[])
  
   in function  utils:'-parse_to/1-fun-1-'/1
  
   in call from lists:'-filter/2-lc$^0/1-0-'/2
  </code></pre>
  
  <p>But if i:</p>
  
  <pre><code>io:format(lists:nth(1,lists:nth(1,Sep1))).
  &gt; Message-ID
  </code></pre>
  
  <p>What's wrong?</p>
  
  <p>Thank you.</p>