     annotation: pd.Series,
                figsize: tuple=None) -&gt; p9.ggplot:
    &#34;&#34;&#34;Plot distribution of number of ES genes per group
    
    Computes the number of ES genes per column, e.g. cell(-type) 
    and plots the distribution for the groups specified
    by the annotation.
    
    Parameters
    ----------
    df : DataFrame
        Dataframe containing positive ES weights, ideally use only ESmu.
    annotation : Series
        Annotation to group dataframe cell(-types) by in the