4.1 Functions4.1.1 Under the hood4.1.2 Function template4.1.3 Arguments4.1.4 Multiple arguments4.1.5 Default arguments4.1.6 Argument name matching4.1.7 Partial matching4.1.8 Scope4.2 Packages4.2.1 Installing packages4.2.2 How does R (not) know about this function?4.2.3 Namespaces4.3 Messages, warnings, and errors, oh my!4.3.1 Creating messages, warnings, and errors4.3.2 Diagnosing messages, warnings, and errors4.4 Testing4.5 Project: Generalizing a function4.6 Try it yourselfTerminologySummary