想问下正文中的 Ruby 代码如果用 Python 该怎么实现

def run(desc, &block)
puts "\n#{desc} start @ #{Time.now}"
block.call
if !$?.nil?
warn "#{desc} fail" unless $?.success?
puts "#{desc} #{$?.success? ? 'success' : 'fail'} @ #{Time.now}"
exit $?.exitstatus unless $?.success?
end
end

run "cd" do
system 'mkdir test' unless File.exist?('test')
system "cd test"
end

run "ls" do
system "ls"
end

其实主要是不知道block该怎么改写