xxxxxxxxxx
> { one: 1, two: 2, three: 3 }.slice(:one, :two)
=> {:one=>1, :two=>2}
# From an array of hash
people = [{name: "david", age: 40, admin: true}, {name: "lisa", age: 27, admin: false}, {name: "bob", age: 23, admin: false}]
ages = people.map { |p| p.slice(:age) }
=> [{:age=>40}, {:age=>27}, {:age=>23}]