, which it’s an simple IDE (integrated development environment) for beginners.
or Ctrl+N to open another window which we can write code in.print("Hello World!") , it should shown like this: 
or F5 to run your code. If it’s the first time you run, it will promote you to save it first.
Some code in this handout have a Run button under it, you can directly run it and edit it without leaving the page. Here’s an example:
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