Finished the extract() function.
Its output can be found in my SVN trunk, in fgdc_files/fgdc_terms.txt

Steps to get this output:
1. save FGDC standard as a .txt document.
2. Run the paths() function to create a dictionary of each term and its hierarchy path.
3. Pass the dictionary to dictWriter(), to save it.
Or put it directly into extract(), as a parameter.
4. Run extract(). It will ask for the following file paths:

• FGDC Standard
• FGDC hierarchy
• Where to put the output
• URL of FGDC Standard
  

NOTE: Not all of the terms in fgdc_terms.txt have hierarchy paths, due to inconsistencies between the FGDC standard and the hierarchy XML file.