st of rowspans and colspans occupied by each subplot.
    subplot_list : list of subplots
        List of subplots that will be used to calculate optimal subplot_params.
    pad : float
        Padding between the figure edge and the edges of subplots, as a
        fraction of the font size.
    h_pad, w_pad : float
        Padding (height/width) between edges of adjacent subplots, as a
        fraction of the font size.  Defaults to *pad*.
    rect : tuple
        (left, bottom, right, top), default: None.
    z	font.size)