Question: I am try to create a regular expression for a javascript project that covers every hyperlink that starts with "file://"

Thanks :)

Answer: 
In Ruby you must initialize a variable before using it (looks like a sound policy...). Note also that what you wrote is not idiomatic Ruby, an alternative:

```
months = {"Feb" => 0.upto(4).map { |i| "day#{i}" }}

```

To update:

```
months["Feb"] = 0.upto(4).map { |i| "day#{i}" }

```
```
# the ||= set this to an empty hash({}) if it hasn't been initialized yet
months ||= {}

#updated as you like, use symbols :feb over string "feb" as the key (read this in other questions in this website)
months[:feb] = (0..4).map {|n| "day#{n}"}

p months  #==> {:feb=>["day0", "day1", "day2", "day3", "day4"]}

```