这个问题已经发生了好多次了，不知道怎么解决。有人在TTR包中处理过这个错误吗？
library('TTR')
symbols <- TTR::stockSymbols()
Fetching AMEX symbols...
Error in file(file, "rt") : cannot open the connection
In addition: Warning message:
In file(file, "rt") : InternetOpenUrl failed: 'The operation timed out'