public class PerformanceTest {
    
    public void insert10Times() {
        Document doc = new Document()
        .append("hello", "world");
        
        for (int i = 0; i < 10; i++) {
            collection.insertOne(doc);
        }
    }
}

// Somewhere inside the code of `insertOne` method
if(doc.get("_id") == null) {
    doc.put("_id", new ObjectId());
}

Execution error (MongoWriteException) at com.mongodb.client.internal.MongoCollectionImpl/executeSingleWriteRequest 
(MongoCollectionImpl.java:1032).
Write operation error on server localhost:27017. Write error: 
WriteError{code=11000, 
message='E11000 duplicate key error collection: db_for_test.40b37bce-142d-4f7d-b6a6-4580bdc55ca2 
index: _id_ dup key: { _id: ObjectId('65188e6c1cd8c84dfe5af4ab') }', details={}}.

public class PerformanceTest {
    
    public void insert10Times() {
        Document doc = new Document()
        .append("hello", "world");
        
        for (int i = 0; i < 10; i++) {
            collection.insertOne(doc);
            doc.remove("_id");
        }
    }
}

function moveToPreviousMonth(date) {
    date.setMonth(date.getMonth() - 1);
    // Set the day to either 28. 29, 30, or 31
    date.setDate(date.daysInMonth());
}

function moveToNextMonth(date) {
    // Set the day first, since the next month
    // might not have 31 days
    date.setDate(1);
    date.setMonth(date.getMonth() + 1);
}

function moveToNextMonth(date) {
    date.setMonth(date.getMonth() + 1);
    date.setDate(1);
}

function easiness(levelOfExpertise) {
    if (logEnabled) {
        console.log("easiness called");
    }
    if (levelOfExpertise >= SENIOR) {
        return "easy";
    } else {
        return "hard";
    }
}

(defn simplicity [system]
  (if log-enabled
    (println "simplicity called"))
  (if (stateful? system)
    :complex
    :simple))

(defn simplicity [system]
  #_(if log-enabled
      (println "simplicity called"))
  (if (stateful? system)
    :complex
    :simple))