The answer to this is yes. The code you would use is not specific to the API, however. You can use any code libraries available for Python. I use pandas, which is an excellent code library for data analysis and data preparation. One of the primary data structures in pandas is the DataFrame, which can be thought of as just like a table in a database. The options for joins (called 'merges' in pandas) mimic those of SQL.
The current Tableau extract api only supports a single table. To import multiple tables, you would have to denormalize them as part of extracting your data (ie (simplified) instead of "SELECT * FROM Foo" you might have "SELECT * FROM Foo JOIN Bar on Foo.x = Bar.y". Then insert the denormalized resultset into the tde. Hope that helps clarify things for you. Thanks