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<p>
  The case expression is the most common kind of flow control in Gleam code. It
  is similar to <code>switch</code> in some other languages, but more powerful
  than most.
</p>
<p>
  It allows the programmer to say "if the data has this shape then run this
  code", a process called <em>pattern matching</em>.
</p>
<p>
  Gleam performs <em>exhaustiveness checking</em> to ensure that the patterns in
  a case expression cover all possible values. With this you can have confidence
  that your logic is up-to-date for the design of the data you are working with.
</p>
<p>
  Try commenting out patterns or adding new redundant ones, and see what
  problems the compiler reports.
</p>