code: def _run_interface(self, runtime):
      runtime.returncode = 0
      self._results["output1"] = self.inputs.input1 + self.inputs.inc
      return runtime
  
imports: import pytest
  from ....None import config
  from ...None import engine
  from ....interfaces import base
  from ....interfaces.utility import IdentityInterface, Function, Merge
  from ....interfaces.base import traits, File
label_desc: Use image node_id 1 for calling the IncrementInterface obj's underlying member method code with example usage: obj._run_interface(runtime) and returns: runtime