Highlight a span on a timeseries plot using pandas and matplotlib

gistfile1.py

def render_split(time, color, offset = -4*pd.datetools.Minute(15)):
    if(color is not None):
        pl.gca().axvspan(
                time + offset, 
                time + pd.datetools.Minute(15) + offset,
                facecolor = pl.cm.Paired( float(color % 12)/12 ),
                linewidth = 0,
                alpha = 1.0,
        )