default set to boolean False, help as a string "Just show what migrations would be made; don't actually write them.". call the method parser.add_argument with 5 arguments: string '--merge', action as a string 'store_true', dest as a string 'merge',
parser . add_argument ( '--merge' , action = 'store_true' , dest = 'merge' , default = False , help = "Enable fixing of migration conflicts." )