def step_input(CurrTime, Amp, StartTime = 0.0):
    """
    Function to create a step input

    Arguments:
      CurrTime : The current timestep (will also take an array)
      Amp : The size of the step input
      StartTime : The time that the step should occur

    Returns:
      The step input for the CurrTime timestep or an array representing the
      step input over the times pass
    """

    return Amp * (CurrTime > StartTime)