title: Using builtin 'str' function in web.py templates: global name not found
body: <p>I've spent way too much time trying to figure this out:</p>
  
  <p>I'm passing a template a number like so and trying to make it a string:</p>
  
  <p>$def with (num)</p>
  
  <p>$(str(num))
  or
  $str(num)</p>
  
  <p>This generates an error saying global name "str" not found.</p>
  
  <p><strong>Edit &amp; Solution</strong>: I'm doing this so I can refer to "img[0-n].png". If num is passed as a number, you can make this string by just saying "img$(num).png". No need to convert num to string explicitly.</p>