A couple of additions to Ruby Hash

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class Hash
  # names = {
  #   :first  => 'ryan',
  #   :middle => 'paul',
  #   :last   => 'heath'
  # }
  #
  # names.has_keys? :first, :last
  # => true
  # names.has_keys? :first, :title
  # => false
  def has_keys?(*keys)
    keys.each do |key|
      return false unless has_key?(key)
    end
    return true
  end

  # names.pairs :first, :last
  # => {:first => 'ryan', :last => 'heath'}
  # names.pairs :middle
  # => {:middle => 'paul'}
  def pairs(*keys)
    keys.inject({}) { |h,k| h[k] = self[k]; h }
  end
end