StepsWithScenarioContextParallel.cs

[Binding]
public class CalculatorSteps
{
  private readonly ScenarioContext scenarioContext;

  public CalculatorSteps(ScenarioContext scenarioContext)
  {
    this.scenarioContext = scenarioContext;
  }

  [Given(@"I have entered (.*) into the calculator")]
  public void GivenIHaveEnteredIntoTheCalculator(int operand)
  {
    ((Calculator)scenarioContext["calc"]).Enter(operand);
  }
  //...
}