Integrate

@staticmethod
def evaluate(argument: "WaveformVariable | np.ndarray") -> float:
    """
    Integrate a waveform or image. Errors if scalar provided.

    Waveform:
    First, applies smoothing by taking weighted nearest and next-nearest
    neighbour contributions to  y values whose difference from their neighbours
    is more than 0.2 times the total range in y.
    The y values are then integrated with respect to x, with the last y value
    neglected.

    Image:
    Return the sum of all pixel values.
    """
    if isinstance(argument, WaveformVariable):
        Builtin.smooth(argument.y)
        return np.sum(argument.y[:-1] * np.diff(argument.x))
    elif isinstance(argument, np.ndarray):
        return np.sum(argument)
    else:
        # The check will fail and raise a TypeError
        Integrate.evaluation_type_check(argument)