def correlation_function(x, y):
    """
    Get correlation between 2 arrays.

    Parameters
    ----------
    x : ~pytil.numpy.ArrayLike[float]
    y : ~pytil.numpy.ArrayLike[float]

    Returns
    -------
    float
        Correlation between ``x`` and ``y``
    """
    raise Exception(
        'This is an abstract function intended to be referenced in documentation only, do not call it in code'
        )
