code: def test_empty_tuple(sym):
      t = parse("()", sym)
      assert isinstance(t, ct.DataShape)
      assert isinstance(t.measure, ct.Tuple)
      assert t.measure.dshapes == ()
  
imports: from __future__ import absolute_import, division, print_function
  import unittest
  import pytest
  from datashader import datashape
  from datashader.datashape.util.testing import assert_dshape_equal
  from datashader.datashape.parser import parse
  from datashader.datashape import coretypes
  from datashader.datashape import DataShapeSyntaxError
label_desc: Use image node_id 4 for calling a global function with example usage: test_empty_tuple(sym) without return types