title: sum of two numbers coming from the command line
body: <p>I know it's a very basic program but I am getting an error of list out of range. Here is the program to take two numbers as command-line arguments (while invoking the script) and display sum (using python):</p>
  
  <pre><code>import sys
  a= sys.argv[1]
  b= sys.argv[2]
  sum=str( a+b)
  print " sum is", sum    
  </code></pre>