Add optional argument

demo.py

@@ -0,0 +1,18 @@
+# author: Tiffany Timbersy
+# date: 2020-01-15
+
+"""This script prints out docopt args.
+Usage: demo.py <arg1> --arg2=<arg2> [--arg3=<arg3>] [--arg4=<arg4>]
+
+Options:
+<arg>             Takes any value (this is a required positional argument)
+--arg2=<arg2>     Takes any value (this is a required option)
+[--arg3=<arg3>]   Takes any value (this is an optional option)
+[--arg4=<arg4>]   Takes any value (this is an optional option)
+""" 
+
+from docopt import docopt
+opt = docopt(__doc__)
+print(opt["--arg4"])
+print(opt)
+print(type(opt))