anchor.diff:  import java.security.MessageDigest;
   import java.util.concurrent.Callable;
   
  -@Command(name = "checksum", mixinStandardHelpOptions = true, version = "checksum 4.0",
  +@Command(name = "checksum", mixinStandardHelpOptions = true, version = "checksum 4.5",
            description = "Prints the checksum (MD5 by default) of a file to STDOUT.")
   class CheckSum implements Callable<Integer> {
   
  
positive.code: // The goal of the introduction is to show how easy picocli is.
  // (The rest of this document has plenty of details.)
  
  .Kotlin
  [[CheckSum-App-Kotlin]]
  [source,kotlin,role="secondary"]
  
negative.code: }
  
  fun main(args: Array<String>) : Unit = exitProcess(CommandLine(Checksum()).execute(*args))
  ----
  
  .Scala
  [[CheckSum-App-Scala]]
  [source,scala,role="secondary"]
  ----
  import java.io.File
  import java.util.concurrent.Callable
  import java.math.BigInteger
  import java.nio.file.Files
  import java.security.MessageDigest
  
  import picocli.CommandLine
  import picocli.CommandLine.{Command, Option, Parameters}
  
  @Command(name = "checksum", version = Array("Checksum 4.5"),  mixinStandardHelpOptions = true,
    description = Array("Prints the checksum (MD5 by default) of a file to STDOUT."))
  class Checksum extends Callable[Int] {
  
    @Parameters(index = "0..*", description = Array("The file whose checksum to calculate."))
    private val file : File = null
  
    @Option(names = Array("-a", "--algorithm"), description = Array("MD5, SHA-1, SHA-256, …"))
    private var algorithm = "MD5"
  
    def call(): Int = {
      val fileContents = Files.readAllBytes(file.toPath)
      val digest = MessageDigest.getInstance(algorithm).digest(fileContents)
      println(("%0" + digest.size * 2 + "x").format(new BigInteger(1, digest)))
      0
    }
  }
  
  object Checksum {
    def main(args: Array[String]): Unit = {
      System.exit(new CommandLine(new Checksum()).execute(args: _*))
    }
  }
  ----
  
  [TIP]
  