class Faraday::Options

def merge!(other)
  other.each do |key, other_value|
    self_value = send(key)
    sub_options = self.class.options_for(key)
    new_value = if self_value && sub_options && other_value
                  self_value.merge(other_value)
                else
                  other_value
                end
    send("#{key}=", new_value) unless new_value.nil?
  end
  self
end