code: def test_erf_(self):
      self.run_test(
          "def erf_(a):\n from math import erf\n return erf(a)",
          1,
          erf_=[int],
      )
  
imports: from pythran.tests import TestEnv
label_desc: Use image node_id 29 for calling the TestMath obj's underlying member method code with example usage: obj.test_erf_() without return types