def validate(self):
            """
            Validation rules that don't require any extra context go here.
            """
            super().validate()
            if self.use_exec and self.capture_stdout:
                raise ConfigValidationError(
                    "'use_exec' and 'capture_stdout'"
                    " options cannot be both provided on the same task."
                )

            Validation rules that don't require any extra context go here.
            
poethepoet/task/cmd.py