The use statement should be

use WWW:Curl::Easy;
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as it makes the constant CURLOPT_URL available.

If you had use strict; in your program it would have pointed out the error

Bareword "CURLOPT_URL" not allowed while "strict subs" in use at Perl-
+2.pl line 13.
Execution of Perl-2.pl aborted due to compilation errors.
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