message: fixed lifetime problem
diff: @@ -67,7 +67,7 @@ where
  /// `cost_function`: cost function
  /// `init_param`: Initial parameter vector
  pub fn new(
  - operator: Box<ArgminOperator<Parameters = T, OperatorOutput = T, Hessian = ()>>,
  + operator: Box<ArgminOperator<Parameters = T, OperatorOutput = T, Hessian = ()> + 'a>,
  b: T,
  init_param: T,
  ) -> Result<Self, Error> {
  