title: How to count number of lines after a certain line
body: <p>I am trying to write a code that will count number of lines after <em>certain</em> line. I would like to compute all the lines that appear in my file after {A   B} appearing in my file</p>
  
  <pre><code>{A   B}
  1     1
  0.072 108.815
  0.217 108.815
  0.362 108.814
  </code></pre>
  
  <p>My code is as follows:</p>
  
  <pre><code>from __future__ import with_statement
  def file_len(fname):
     with open(fname) as f:
          for i, l in enumerate(f):
               pass
     return i + 1
  
  t=file_len("test.ghx")
  print t
  </code></pre>
  
  <p>I am not sure how I can modify this to count the number of lines after specific line that includes {A   B}.</p>
  
  <p>Can anyone share some thoughts?</p>