argparse(Python command-line parsing library)

• The argparse module makes it easy to write user friendly command line interfaces.
• The program defines what arguments it requires, and argparse will figure out how to parse those out of sys.argv. 
• The argparse module also automatically generates help and usage messages and issues errors when users give the program invalid arguments.
• As of Python >= 2.7 and >= 3.2, the argparse module is maintained within the Python standard library. 
• For users who still need to support Python < 2.7 or < 3.2, it is also provided as a separate package, which tries to stay compatible with the module in the standard library, but also supports older Python versions.