getSymbols我在使用该包的几天里一直在 R 中遇到错误消息quantmod：
Error in new.session() : Could not establish session after 5 attempts.
getSymbols(tick, from = date_from, to = date_to, warnings = FALSE, auto.assign = TRUE)
同样的问题也适用于：
getSymbols(tick, from = date_from, to = date_to, warnings = FALSE, auto.assign = TRUE, src="yahoo")