The `if let intensity = intensity {} else {}` is repetitive. How would I create a function to replace this repetitive code? Or what other tool could I use?

I'm new to this all. Any help appreciated.

```
func process(filters: [String], intensity: Int? = nil) {
    for filter in filters {
        switch filter {
            case "blue":
                if let intensity = intensity {
                    self.blue(value: intensity)
                } else {
                    self.blue()
                }

            case "contrast":
                if let intensity = intensity {
                    self.contrast(value: intensity)
                } else {
                    self.contrast()
                }

            case "blackAndWhite":
                if let intensity = intensity  {
                    self.blackAndWhite(value: intensity)
                } else {
                    self.blackAndWhite()
                }

            case "halfBrightness":
                if let intensity = intensity {
                    self.halfBrightness(value: intensity)
                } else {
                    self.halfBrightness()
                }

            case "doubleBrightness":
                if let intensity = intensity {
                    self.doubleBrightness(value: intensity)
                } else {
                    self.doubleBrightness()
                }

            default:
                print("The filter you specified doesn't exist.")
        }
    }
}

```