It is possible to retrieve the open svg's file path from within an extension?

Perhaps something like this :

my_svg_filepath = self.document_path()

# Check to see if user has saved file at least once
if len(my_svg_filepath) < 2:
    inkex.errormsg('Please Save Your File First')
else:
    inkex.errormsg(my_svg_filepath)

Thank you.