Assign value if not exist in Go

In Go, you can assign a value if it does not exist using the following syntax:

if _, ok := myMap[key]; !ok {
    myMap[key] = value
}

This assigns the value value to the key key in the myMap map only if that key does not already exist in the map.

Here's an example:

myMap := make(map[string]string)
// You can assign a value to a key in myMap

myMap["key1"] = "value1"
// Now let's try to assign a value to "key1" again

if _, ok := myMap["key1"]; !ok {

    myMap["key1"] = "new_value1"

}
// "key1" already exists, so its value should be unchanged

fmt.Println("myMap['key1']: ", myMap["key1"]) // Output: myMap['key1']: value1
// Let's try again with a new key

if _, ok := myMap["key2"]; !ok {

    myMap["key2"] = "value2"

}
// "key2" does not exist yet, so its value should be added to myMap

fmt.Println("myMap['key2']: ", myMap["key2"]) // Output: myMap['key2']: value2

In this example, "key1" already exists in myMap, so it is not assigned a new value. However, since "key2" does not exist yet, it is assigned the value "value2".