problem creating folder on datastore

I'm new to pyvmomi and python, so please forgive the 'newbie' question:

OBJECTIVE: use pyvmomi to create new folder on the local datastore

Using the following sample code (see url) and made a few modifications by

adding the following code (see below).  However I get the following error.

ERROR: TypeError: _InvokeMethod() takes at least 2 arguments (1 given)

QUESTION: How can I fix this error?  I'm passing 2 arguments in the code.

NOTE: I can use other sample scripts (e.g. powerOn) passing same info

and it works.

CMD LINE: ....\pyvmomi-community-samples-master> python samples\list_datastore_info.py -s myIP -u myUsername -p myPassword

https://github.com/vmware/pyvmomi-community-samples/blob/master/samples/list_datastore_info.py

CODE:

....

....

atexit.register(connect.Disconnect, service_instance) content = service_instance.RetrieveContent()

#START MY CODE:

dc = content.rootFolder.childEntity[0]

newName = "[local__local] cache"

fm = vim.FileManager

fm.MakeDirectory(name=newName,datacenter=dc)

#END MY CODE:

....

....

Any thoughts are greatly appreciated!