title: python sorting lines in a file beginning with numbers in the right order
body: <p>I have a file which looks like:</p>
  <pre><code>11 -7.072985E-17  5.570644E-18  2.763979E-17
  12 -6.420375E-17 -5.456010E-19  2.229937E-17
  9 -8.360102E-17  1.172390E-17  2.492073E-17
  10 -1.046834E-16  1.106907E-17  1.840354E-17
  17  2.000000E-01  1.172390E-17  2.492073E-17
  18  2.000000E-01  1.106907E-17  1.840354E-17
  19  2.000000E-01  5.570644E-18  2.763979E-17
  20  2.000000E-01 -5.456010E-19  2.229937E-17
  2  0.000000E+00  0.000000E+00  0.000000E+00
  6  2.000000E-01  0.000000E+00  0.000000E+00
  4  0.000000E+00  0.000000E+00  0.000000E+00
  1  0.000000E+00  0.000000E+00  0.000000E+00
  13 -8.360102E-17  1.172390E-17  2.492073E-17
  14 -1.046834E-16  1.106907E-17  1.840354E-17
  15 -7.072985E-17  5.570644E-18  2.763979E-17
  16 -6.420375E-17 -5.456010E-19  2.229937E-17
  3 -0.000000E+00 -0.000000E+00 -0.000000E+00
  5  2.000000E-01 -0.000000E+00 -0.000000E+00
  7  2.000000E-01 -0.000000E+00 -0.000000E+00
  8  2.000000E-01 -0.000000E+00 -0.000000E+00
  21  2.000000E-01  1.172390E-17  2.492073E-17
  22  2.000000E-01  1.106907E-17  1.840354E-17
  </code></pre>
  <p>how can i order the lines so that it will change the order of it resulting in lines starting  with 1,2,.... looking like:</p>
  <pre><code>1  0.000000E+00  0.000000E+00  0.000000E+00
  2  0.000000E+00  0.000000E+00  0.000000E+00
  .....
  21  2.000000E-01  1.172390E-17  2.492073E-17
  
  </code></pre>