## [line 150](https://github.com/realworldocaml/examples/blob/master/code/guided-tour/main.topscript) should be modified. - In latest version of Core library the to_sec_string function has new interface > `val to_sec_string : t -> zone:Zone.t -> string` see more details [here](http://stackoverflow.com/questions/34219020/convert-time-into-seconds-string-issue)
