def startmultipartbody(self, subtype, boundary=None, plist=[], prefix=1):
        self._boundary = boundary or mimetools.choose_boundary()
        return self.startbody("multipart/" + subtype,
                              [("boundary", self._boundary)] + plist,
                              prefix=prefix)
Test convenience method for axis label setting
dataset/ETHPy150Open Southpaw-TACTIC/TACTIC/src/context/client/tactic-api-python-4.0.api04/Lib/MimeWriter.py/MimeWriter.startmultipartbody--crossover with--dataset/ETHPy150Open wrobstory/vincent/tests/test_vega.py/TestVisualization.test_axis_labeling