code: def test_tan():
      a = tan(interval(0, np.pi / 4))
      assert a.start == 0
      # must match lib_interval definition of tan:
      assert a.end == np.sin(np.pi / 4) / np.cos(np.pi / 4)
  
      a = tan(interval(np.pi / 4, 3 * np.pi / 4))
      # discontinuity
      assert a.is_valid is None
  
imports: from sympy.external import import_module
  from sympy.plotting.intervalmath import Abs, acos, acosh, And, asin, asinh, atan, atanh, ceil, cos, cosh, exp, floor, imax, imin, interval, log, log10, Or, sin, sinh, sqrt, tan, tanh
label_desc: Use image node_id 8 for calling a global function with example usage: test_tan() without return types