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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def submesh(self, faces_sequence, **kwargs):
 """ Return a subset of the mesh. Parameters faces_sequence : sequence (m,) int Face indices of mesh only_watertight : bool Only return submeshes which are watertight append : bool Return a single mesh which has the faces appended. if this flag is set, only_watertight is ignored Returns --------- if append : trimesh.Trimesh object else : list of trimesh.Trimesh objects """

        return util.submesh(mesh=self,
                            faces_sequence=faces_sequence,
                            **kwargs)