The easy way to deal with my is to simply erase the two letters of m and y, and use the normal rules for parsing. So

my ($a) = <STDIN>;
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acts like

   ($a) = <STDIN>;
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and

my $a = <STDIN>;
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acts like

   $a = <STDIN>;
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Once you get that you just "erase the my" and continue the parse, it's simple to reduce to cases you've already known.

-- Randal L. Schwartz, Perl hacker