def identity(x):
    """Identity activation Layer
    A placeholder identity operator that is argument-insensitive.

    Args:
        x (np.ndarray): input tensor.

    Returns:
        (np.ndarray): output tensor and have same shape with x.

    Examples:
        >>> identity(np.array([-3.0, -1.0, 0.0, 2.0]))
        tensor([-3.0, -1.0, 0.0, 2.0])

    """
    return x