code: def _run(self, x):  # type: ignore
      return (self._erf(x).astype(x.dtype),)
  
imports: from math import erf
  import numpy
  from onnx.reference.ops._op import OpRunUnaryNum
label_desc: Use image node_id 2 for calling the Erf obj's underlying member method code with example usage: obj._run(x) and returns: self