Global symbol "$key" requires explicit package name at ./parse.pl line
+ 29. 
Global symbol "$value" requires explicit package name at ./parse.pl li
+ne 29.
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you forgot my

while (my ($key, $value) = each %{$xmlRef})

edit

For historic reasons package variables ("global symbols") are the default in Perl, lexical variables were introduced later.

Under strict it's necessary to declare explicitly with our or my which kind of variable you want ¹)

This has the advantage over Python's implicit declaration to catch typos more easily.

update