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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def meta_bar_chart(series=None, N=20):
    "Each column in the series is a dict of dicts"
    if not series or isinstance(series, basestring):
        series = json.load(load_app_meta)
    if isinstance(series, Mapping) and isinstance(series.values()[0], Mapping):
        rows_received = series['# Received'].items()
    elif isinstance(series, Mapping):
        rows_received = series.items()
    else:
        rows_received = list(series)

    #rows = sorted(rows, key=operator.itemgetter(1), reverse=True)
    rows = sorted(rows_received, key=lambda x: x[1], reverse=True)
    received_names, received_qty = zip(*rows)
    ra_qty = [(series['Qty in RA'].get(name, 0.) or 0.) for name in received_names]
    # percent = [100. - 100. * (num or 0.) / (den or 1.) for num, den in zip(received_qty, ra_qty)]

    # only care about the top 30 model numbers in terms of quantity
    #ind = range(N)

    figs = []

    figs += [plt.figure()]
    ax = figs[-1].add_subplot(111)
    ax.set_ylabel('# Units Returned')
    ax.set_title('Most-Returned LCDTV Models 2013-present')
    x = np.arange(N)
    bars1 = ax.bar(x, received_qty[:N], color='b', width=.4, log=1)
    bars2 = ax.bar(x+.4, ra_qty[:N], color='g', width=.4, log=1)
    ax.set_xticks(range(N))
    ax.set_xticklabels(received_names[:N], rotation=35)
    ax.grid(True)
    ax.legend((bars1[0], bars2[0]), ('# in RA', '# Received'), 'center right')
    figs[-1].show()