[Errno 13] Permission denied: 'python_repos.svg' 错误，无法生成

import requests
import pygal
from pygal.style import LightColorizedStyle as LCS ,LightenStyle as LS 

URL='https://api.github.com/search/repositories?q=language:python&sort=stars'
r=requests.get(URL)
print("Status code:",r.status_code)
response_dict=r.json()
print("Total repositories:",response_dict['total_count'])
repo_dicts=response_dict['items']

names,stars=[],[]
for repo_dict in repo_dicts:
    names.append(repo_dict['name'])
    stars.append(repo_dict['stargazers_count'])

my_style=LS('#333366',base_style=LCS)
chart=pygal.Bar(style=my_style,x_label_rotation=45,show_legend=False)
chart.title='Most-Starred Python Projects on GitHub'
chart.x_labels=names
chart.add('',stars)
chart.render_to_file('pthon_repos.svg')

就是最后一步生成错误，无法生成文件，源代码我也看了跟我一样。各位看看有什么可以错误

看看是不是 pthon_repos.svg 已经存在了。
改个新名字试试。