text: #!/usr/bin/env python
  
  import sys
  #An example program that evaluates simple expressions
  #Takes in a single arg, which is a string to be evaluated
  #Ex. math_val.py "add 1 2 3 4"
  
  cmd = sys.argv[1]
  cmd_args = cmd.split(" ")
  try:
      if cmd_args[0].lower() == "add":
          result = 0
          for arg in cmd_args[1:]:
              result = result + int(arg)
          print "result="+str(result)
          sys.exit(0)
  
      elif cmd_args[0].lower() == "mul":
          result = 1;
          for arg in cmd_args[1:]:
              result = result * int(arg)
          print "result="+str(result)
          sys.exit(0)
      else:
          print "error: unknown command"
          sys.exit(-1)
  except ValueError:
      print "error: unexpected input"
      sys.exit(-1)
  