title: Key error when using dictionary definitions
body: <p>I am using the following code which is producing a key error (1, 2) and I'm not sure why:</p>
  
  <pre><code>import concurrent.futures
  import urllib.request
  import json
  
  
  myurls2 = {}
  for x in range(1, 15):
      for y in range(1, 87):
  
          strvar1 = "%s" % (x)
          strvar2 = "%s" % (y)
  
          with open("C:\\Python33\\NASDAQ Stock Strings\\NASDAQ_Config_File_{}_{}.txt".format(x,y),"r") as f:
              myurls2[x,y] = f.read().replace('\n', '')            
              #print("myurls_" + str(strvar1) + "_" + str(strvar2) + "=", myurls2[x,y])
              #print(myurls2[x,y])
  
              URLS = [myurls2[1,1],myurls2[1,2],myurls2[1,3],myurls2[1,4],myurls2[1,5]]
  </code></pre>
  
  <p>When the line '#print(myurls2[x,y])' is uncommented you can see that the dictionary definition is correctly iterating through the text files that generate the dictionary values, but the dictionary keys cannot then be referenced.</p>