code: def test_log():
      a = log(interval(1, 2))
      assert a.start == 0
      assert a.end == np.log(2)
      a = log(interval(-1, 1))
      assert a.is_valid is None
      a = log(interval(-3, -1))
      assert a.is_valid is False
      a = log(-3)
      assert a.is_valid is False
      a = log(2)
      assert a.start == np.log(2)
      assert a.end == np.log(2)
  
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 3 for calling a global function with example usage: test_log() without return types