Operators
https://metacpan.org/pod/perlop
http://perldoc.perl.org/perlintro.html#Builtin-operators-and-functions
- Operator Precedence and Associativity : https://metacpan.org/pod/perlop#Operator-Precedence-and-Associativity
- Equality operators : https://metacpan.org/pod/perlop#Equality-Operators