class Hash

def extract!(*keys)

hash # => {:c=>3, :d=>4}
hash.extract!(:a, :b) # => {:a=>1, :b=>2}
hash = { a: 1, b: 2, c: 3, d: 4 }

Removes and returns the key/value pairs matching the given keys. 
def extract!(*keys)
  keys.each_with_object(self.class.new) { |key, result| result[key] = delete(key) if has_key?(key) }
end