Limit number of checked checkboxes for bokeh plot

The following code generates a bokeh plot with checkboxes that can make graphs visible/invisible. It works great, but I would like to know if it's possible to limit the number of allowed checked checkboxes, for example no more than 2 at the time.

import numpy as np
from bokeh.io import output_file, show
from bokeh.layouts import row
from bokeh.palettes import Viridis3
from bokeh.plotting import figure
from bokeh.models import CheckboxGroup, CustomJS

output_file("line_on_off.html", title="line_on_off.py example")

p = figure()
props = dict(line_width=4, line_alpha=0.7)
x = np.linspace(0, 4 * np.pi, 100)
l0 = p.line(x, np.sin(x), color=Viridis3[0], legend="Line 0", **props)
l1 = p.line(x, 4 * np.cos(x), color=Viridis3[1], legend="Line 1", **props)
l2 = p.line(x, np.tan(x), color=Viridis3[2], legend="Line 2", **props)

checkbox = CheckboxGroup(labels=["Line 0", "Line 1", "Line 2"],
                         active=[0, 1, 2], width=100)
checkbox.callback = CustomJS.from_coffeescript(args=dict(l0=l0, l1=l1, l2=l2, checkbox=checkbox), code="""
l0.visible = 0 in checkbox.active;
l1.visible = 1 in checkbox.active;
l2.visible = 2 in checkbox.active;
""")

layout = row(checkbox, p)
show(layout)

I think this can be done in javascript, but I don't know how to acces the javascript involved here. Could I just write javascript and integrate it with my bokeh plot somehow? I would really appreciate the help!