I had a piece of code which I copied and pasted today.
the line was match = line.split /\s+/ .pop! the error was unexpected assign. after finally changing all variable names I found out that match is a keyword. there should be some mention of not being able to assign to the match keyword, IMO -- totally low priority.
match = line.split /\s+/ .pop!
fix #237 - error on assigning LS reserved word