title: referencing a variable filename
body: <p>Hi i am trying to write a python script in blender that involves the following command:</p>
  
  <pre><code>bpy.ops.wm.save_as_mainfile(filepath = r"C:\Users\mrryan\Desktop\ 'customer_id' + orangecube.blend)
  </code></pre>
  
  <p>The idea is that the script saves the file using both a variable and a standard file name'
  for example;</p>
  
  <p>To create <code>3141orangecube.blend</code></p>
  
  <p>I have defined <code>customer_id</code> as:</p>
  
  <pre><code>customer_id = "3141"
  </code></pre>
  
  <p>Without this variable my script works fine, but  suspect an error in the syntax.</p>
  
  <p>Please help.</p>