def source_file(self):
        if os.path.exists(self.filename):
            # A regular text file: open it.
            return open_source(self.filename)

        # Maybe it's in a zip file?
        source = self.file_locator.get_zip_data(self.filename)
        if source is not None:
            return StringIO(source)

        # Couldn't find source.
        raise CoverageException(
            "No source for code '%s'." % self.filename
            )
Return an open file for reading the source of the code unit.
dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/coverage/codeunit.py/CodeUnit.source_file