title: What does the "list name not defined" error mean in python?
body: <p>I'm new to python, and I'm getting an error I can't figure out. 
  The following script:</p>
  
  <pre class="lang-python prettyprint-override"><code>def add_10(list_num):
      list_num = [1,2,3]                                                 
      list_add_10 = []
          for num in list_num:                     
                  list_add_10.append(num + 10)
          print list_add_10   
  </code></pre>
  
  <p>Returns the error: </p>
  
  <pre><code> "NameError Traceback (most recent call last)
  
   &lt;ipython-input-11-73c7e124d6d6&gt; in &lt;module&gt;()
         4     for num in list_num:
         5         list_add_10.append(num + 10)
   ----&gt; 6 print list_add_10
        NameError: name 'list_add_10' is not defined"
  </code></pre>
  
  <p>I think it's just a scope/indentation problem, but any help would be greatly appreciated.</p>