How to use the mapclassify.Quantiles function in mapclassify

import pandas as pd
import geopandas as gpd
import geoplot as gplt
import geoplot.crs as gcrs
import matplotlib.pyplot as plt
import mapclassify as mc

# load the data
obesity_by_state = pd.read_csv(gplt.datasets.get_path('obesity_by_state'), sep='\t')
contiguous_usa = gpd.read_file(gplt.datasets.get_path('contiguous_usa'))
contiguous_usa['Obesity Rate'] = contiguous_usa['state'].map(
    lambda state: obesity_by_state.query("State == @state").iloc[0]['Percent']
)
scheme = mc.Quantiles(contiguous_usa['Obesity Rate'], k=5)


ax = gplt.cartogram(
    contiguous_usa,
    scale='Obesity Rate', limits=(0.75, 1),
    projection=gcrs.AlbersEqualArea(central_longitude=-98, central_latitude=39.5),
    hue='Obesity Rate', cmap='Reds', scheme=scheme,
    linewidth=0.5,
    legend=True, legend_kwargs={'loc': 'lower right'}, legend_var='hue',
    figsize=(8, 12)
)
gplt.polyplot(contiguous_usa, facecolor='lightgray', edgecolor='None', ax=ax)

plt.title("Adult Obesity Rate by State, 2013")
plt.savefig("obesity.png", bbox_inches='tight', pad_inches=0.1)

# use the Orthographic map projection (e.g. a world globe)
ax = geoplot.polyplot(
    world, projection=geoplot.crs.Orthographic(), figsize=(8, 4)
)
ax.outline_patch.set_visible(True)

###############################################################################
# ``polyplot`` is trivial and can only plot the geometries you pass to it. If
# you want to use color as a visual variable, specify a ``choropleth``. Here
# we sort GDP per person by country into five buckets by color, using
# "quantiles" binning from the `Mapclassify `_
# library.

import mapclassify
gpd_per_person = world['gdp_md_est'] / world['pop_est']
scheme = mapclassify.Quantiles(gpd_per_person, k=5)

# Note: this code sample requires geoplot>=0.4.0.
geoplot.choropleth(
    world, hue=gpd_per_person, scheme=scheme,
    cmap='Greens', figsize=(8, 4)
)

###############################################################################
# If you want to use size as a visual variable, use a ``cartogram``. Here are
# population estimates for countries in Africa.

africa = world.query('continent == "Africa"')
ax = geoplot.cartogram(
    africa, scale='pop_est', limits=(0.2, 1),
    edgecolor='None', figsize=(7, 8)
)

This example, taken from the User Guide, plots cities in the contiguous United States by their
population. It demonstrates some of the range of styling options available in ``geoplot``.
"""


import geopandas as gpd
import geoplot as gplt
import geoplot.crs as gcrs
import matplotlib.pyplot as plt
import mapclassify as mc

continental_usa_cities = gpd.read_file(gplt.datasets.get_path('usa_cities'))
continental_usa_cities = continental_usa_cities.query('STATE not in ["AK", "HI", "PR"]')
contiguous_usa = gpd.read_file(gplt.datasets.get_path('contiguous_usa'))
scheme = mc.Quantiles(continental_usa_cities['POP_2010'], k=5)

ax = gplt.polyplot(
    contiguous_usa, 
    zorder=-1,
    linewidth=1,
    projection=gcrs.AlbersEqualArea(),
    edgecolor='white',
    facecolor='lightgray',
    figsize=(8, 12)
)
gplt.pointplot(
    continental_usa_cities, 
    scale='POP_2010',
    limits=(2, 30),
    hue='POP_2010',
    cmap='Blues',