def area_width_normalized_label(var, area_norm=True, width_norm=True):
    """Returns a label for histograms normalized by any combination of
    area/width. For both area and width, the label should be 1/N*dN/d(var).
    """
    if area_norm and width_norm:
        return '#frac{dN}{Nd('+var+')}'
    elif area_norm:
        return '#frac{#Delta('+var+')dN}{Nd('+var+')}'
    elif width_norm:
        return '#frac{dN}{d('+var+')}'
    else:
        return '#frac{#Delta('+var+')dN}{d('+var+')}'