title: Counting backward from an integer using Python range built-in function, related to parse trees
body: <p>**The list range(1,10,-1) Starting at 1, and ending at 10 won't count backwards because the start value-1 isn't greater than the stop value-10.  **  </p>
  
  <p>documentation </p>
  
  <p><strong>range(start, stop[, step])</strong> </p>
  
  <p>This is a versatile function to create lists containing arithmetic progressions. It is most often used in for loops. The arguments must be plain integers. If the step argument is omitted, it defaults to 1. If the start argument is omitted, it defaults to 0.  If step is positive, the last element is the largest start + i * step less than stop; if step is negative, the last element is the smallest start + i * step greater than stop. step must not be zero (or else ValueError is raised).     </p>
  
  <pre><code>for c in range(1,10,-1):
      c +=1
      print c
  </code></pre>
  
  <blockquote>
    <p>></p>
  </blockquote>
  
  <p><strong>so this works instead</strong></p>
  
  <pre><code>for c in range(10,0,-1):
      c +=1
      print c
  </code></pre>
  
  <blockquote>
    <p>11</p>
    
    <p>10</p>
    
    <p>9</p>
    
    <p>8</p>
    
    <p>7</p>
    
    <p>6</p>
    
    <p>5</p>
    
    <p>4</p>
    
    <p>3</p>
    
    <p>2</p>
  </blockquote>