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use open ':encoding(locale)';

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The "open" pragma serves as one of the interfaces to declare default
"layers" (also known as "disciplines") for all I/O. Any two-argument
open(), readpipe() (aka qx//) and similar operators found within the
lexical scope of this pragma will use the declared defaults. Even
three-argument opens may be affected by this pragma when they don't
specify IO layers in MODE.