You might want to read about eval.

eval is sometimes used to probe loading of modules and act accordingly when loading fails by examining $@.

eval { require Foo::Bar };
die $@ if $@;
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is "functionally" almost equal to

use Foo::Bar;
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If you read carefully through the documentation, you'll see there are many other interesting use cases for eval. You should also give Super Search a try since others have already provided useful insight.