title: Confusing behavior of re module regarding tabs
body: <p>As a novice programmer I recently stumbled upon a strange behaviour of my implementation of regex.  Via parsing an excel-file, I fill a dictionary with keys of this structure:</p>
  
  <pre><code>1   21555159    A   T   G   P
  15  2626264985  C   A   R   Q
  X   515151  G   C   D   W
  …
  </code></pre>
  
  <p>The six entries are tab separated and I need them in this form for a query. 
  Later on, I parse another file, where the said keys should be found at the start of some lines (exactly looking as above) with this rather clumsy regular expression:</p>
  
  <pre><code>match = re.search("(^.{1,2}\t\d+\t\D\t\D\t\D\t\D)", line_iterater)
  </code></pre>
  
  <p>Then - match.group() - provides me, for example, this output...</p>
  
  <pre><code>1\t21555159\tA\tT\tG\tP
  </code></pre>
  
  <p>...which, of course, doesn’t match with the key in the dictionary, so I cannot access the corresponding items. </p>
  
  <p>Question: Why is this behaviour of the <code>re</code> module that I get a ‘\t’ for a tab ‘    ‘ 
  or what’s wrong with my understanding of it.</p>
  
  <p>(My naïve remedy was to chance all tabs in the keys with <code>\t</code>)</p>