在尝试运行具有输出直方图的简单代码时，我不断收到以下错误：
Traceback (most recent call last):
File "c:\tmp\die_visual.py", line 1, in <module>
import pygal
File "C:\Users\Christopher\AppData\Roaming\Python\Python36\site-packages\pygal\__init__.py", line 33, in <module>
from pygal.graph.bar import Bar
File "C:\Users\Christopher\AppData\Roaming\Python\Python36\site-packages\pygal\graph\__init__.py", line 24, in <module>
from .__about__ import * # noqa: F401,F403
ModuleNotFoundError: No module named 'pygal.graph.__about__'
我已将需要 pygal 的文件移至同一目录，但出现相同的错误。
这是我输入的代码。
import pygal
from die import Die
# Create a D6.
die = Die()
# Make some rolls, and store results in a list.
results = []
for roll_num in range(1000):
result = die.roll()
results.append(result)
# Analyze the results
frequencies = []
for value in range(1, die.num_sides+1):
frequency = results.count(value)
frequencies.append(frequency)
# Visualize the results.
hist = pygal.Bar()
hist.title = "Results of rolling one D6 1000 times."
hist.x_labels = ['1', '2', '3', '4', '5', '6']
hist.x_title = "Result"
hist.y_title = "Frequency of Result"
hist.add('D6', frequencies)
hist.render_to_file('die_visual.svg')