Parameters
    ----------
    arr: np.ndarray, ExtensionArray, Series
        Input array. If `sorter` is None, then it must be sorted in
        ascending order, otherwise `sorter` must be an array of indices
        that sort it.
    value : array-like or scalar
        Values to insert into `arr`.
    side : {'left', 'right'}, optional
        If 'left', the index of the first suitable location found is given.
        If 'right', return the last such index.  If there is no suitable
        index, return either 0 or N (where N is the length of `self`).
    sorter : 1-D array-like, optional
        Optional array of integer indices that sort array a into ascending
        order. They are typically the result of argsort.

    Returns
    -------
    array of ints or int
        If value is array-like, array of insertion points.
        If value is scalar, a single integer.

    See Also
    --------
    numpy.searchsorted : Similar method from NumPy.
    N