def METHOD_NAME(da, **hist):
    """Concatenate historical scenario with future scenarios along time.
    Parameters
    ----------
    da : xr.DataArray
      Input data where the historical scenario is stored alongside other, future, scenarios.
    hist: {str: str}
      Mapping of the scenario dimension name to the historical scenario coordinate, e.g. `scenario="historical"`.
    Returns
    -------
    xr.DataArray
      Data with the historical scenario is stacked in time before each one of the other scenarios.
    Notes
    -----
    Data goes from:
        +------------+----------------------------------+
        | scenario   | time                             |
        +============+==================================+
        | historical | ``hhhhhhhhhhhhhhhh------------`` |
        +------------+----------------------------------+
        | ssp245     | ``----------------111111111111`` |
        +------------+----------------------------------+
        | ssp370     | ``----------------222222222222`` |
        +------------+----------------------------------+
    to:
        +----------+----------------------------------+
        | scenario | time                             |
        +==========+==================================+
        | ssp245   | ``hhhhhhhhhhhhhhhh111111111111`` |
        +----------+----------------------------------+
        | ssp370   | ``hhhhhhhhhhhhhhhh222222222222`` |
        +----------+----------------------------------+
    """
    if len(hist) > 1:
        raise ValueError("Too many values in hist scenario.")
    # Scenario dimension, and name of the historical scenario
    ((dim, name),) = hist.items()
    # Select historical scenario and drop it from the data
    h = da.sel(**hist).dropna("time", how="all")
    ens = da.drop_sel(**hist)
    index = ens[dim]
    bare = ens.drop(dim).dropna("time", how="all")
    return xr.concat([h, bare], dim="time").assign_coords({dim: index})