Source code can be inline or as blocks. Blocks can have syntaxhighlighting for many different languages.

JavaScript:

function writeHelloWorld(name) {
  console.log(`Hello World and ${name}!`);
}
writeHelloWorld('Jon Doe');
// writes 'Hello World and Jon Doe!' to STDOUT.

Ruby:

def print_helloWorld(name)
  puts "Hello World and #{name}!"
end
print_helloWorld('Jon Doe')
#=> prints 'Hello World and Jon Doe!' to STDOUT.

C#:

void WriteHelloWorld(string name)
{
  Console.WriteLine("Hello World and {0}!", name);
}
WriteHelloWorld("John Doe");
// writes 'Hello World and Johnm Doe' to STDOUT