class Hash

def slice!(*keys)

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

Returns a hash containing the removed key/value pairs.
Replaces the hash with only the given keys. 
def slice!(*keys)
  keys.map! { |key| convert_key(key) } if respond_to?(:convert_key, true)
  omit = slice(*self.keys - keys)
  hash = slice(*keys)
  hash.default      = default
  hash.default_proc = default_proc if default_proc
  replace(hash)
  omit
end