def help():
    """List all targets"""
    print("Please use '{} <target>' where <target> is one of"
          .format(sys.argv[0]))
    width = max(len(name) for name in TARGETS)
    for name, target in TARGETS.items():
        print('  {name:{width}} {descr}'.format(name=name, width=width,
                                                descr=target.__doc__))
List all targets