ImportError: Failed to import any qt binding

Traceback (most recent call last):
File "demo_toolbox.py", line 2, in
from toolbox import Toolbox
File "/Users/Henry/Downloads/MockingBird-main/toolbox/__init__.py", line 1, in
from toolbox.ui import UI
File "/Users/Henry/Downloads/MockingBird-main/toolbox/ui.py", line 2, in
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/matplotlib/backends/backend_qt5agg.py", line 11, in
from .backend_qt5 import (
File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/matplotlib/backends/backend_qt5.py", line 16, in
import matplotlib.backends.qt_editor.figureoptions as figureoptions
File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/matplotlib/backends/qt_editor/figureoptions.py", line 11, in
from matplotlib.backends.qt_compat import QtGui
File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/matplotlib/backends/qt_compat.py", line 175, in
raise ImportError("Failed to import any qt binding")
ImportError: Failed to import any qt binding

Start with demo_toolbox.py and toolbox/ui.py, following the import chain into matplotlib's backend_qt5agg module. Reproduce the import failure and inspect the project's dependency setup; done when importing Toolbox no longer raises the missing Qt binding error.

Written by the indexing model from the issue text.