def post(path, params={})
      signature_params = params.values.any?{|value| value.respond_to?(:to_io)} ? {} : params
      request(:post, path, params, signature_params)
    end
def post(path, params={})
      signature_params = params.values.any?{|value| value.respond_to?(:to_io)} ? {} : params
      request(:post, path, params, signature_params)
    end
Perform an HTTP POST request