Expandable 2D Dictionaries?

[Robert Dailey]

Hi,

I am interested in creating an expandable (dynamic) 2D dictionary. For
example:

myvar["cat"]["paw"] = "Some String"

The above example assumes "myvar" is declared. In order for this to
work, I have to know ahead of time the contents of the dictionary. For
the above to work, my declaration must look like:

myvar = {"cat": {"paw":""} }

I would like to not have to declare my dictionary like this, as it
does not allow it to be expandable. I'm very new to Python (I'm a
professional C++ programmer. Any comparisons to C++ would help me
understand concepts).

Is there a way that when I index into my dictionary using an "unknown"
index (string), that python will dynamically add that key/value pair?

Thanks.