def addColorbar(ax, mappable, norm, cbarLabel=None):
    """
    Quick utility to add a colorbar to an axes object

    Parameters
    ----------
    mappable: iterable
        Collection of meshes, patches, or values that are used to construct
        the colorbar.
    norm: None or :class:`matplotlib.colors.Normalize` subclass
        Normalizer for this plot
    cbarLabel: None or str
        If given, place this as the y-label for the colorbar

    Returns
    -------
    :class:`matplotlib.colorbar.Colorbar`
        The colorbar that was added
    """
    cbar = ax.figure.colorbar(mappable, norm=norm)
    if cbarLabel is not None:
        cbar.ax.set_ylabel(cbarLabel)
    return cbar