def with_headers(extra_headers = {}, &block)
      original_headers = @conn.headers.dup
      @conn.headers.merge!(extra_headers)
      result = yield self
      @conn.headers = original_headers
      result
    end
def with_headers(extra_headers = {}, &block)
      original_headers = @conn.headers.dup
      @conn.headers.merge!(extra_headers)
      result = yield self
      @conn.headers = original_headers
      result
    end
Yields client with temporarily modified headers.

 @param extra_headers [Hash] Additional headers added to next request.
 @yieldreturn [BookingSync::API::Client] Client with modified default headers.
 @return [Array<BookingSync::API::Resource>|BookingSync::API::Resource|String|Object] Client response