see topic as shown at the top.
Surprise! Julia REPL accepts [tab]s for autocompletion. The first [tab] tries to autocomplete ε (the empty string), which gives you ε again, since it is the most ambiguous string. The second [tab] gives you the full list of possible autocompletions of ε, which is all autocompletable strings in Julia, since they all start with ε.
If you want to look up all autocompletions starting with something in the REPL, enter two [tab]s would do the job! E.g. a[tab][tab] would give you all symbols starting with a.