Hi,

irb(main):039:0> hash = Hash.new []
=> {}
irb(main):040:0> hash['abc'] << 3
=> [3]
irb(main):041:0> hash.keys
=> []
irb(main):042:0> hash['def']
=> [3]


Since I have created a key/value pair with hash['abc'] << 3, why
hash.keys show nothing?
And, why hash['abc'] << 3 changed the hash's default value (which
should be an empty array)?

Thanks.