A set of key/value pairs.
Hash can be thought of as an associative array, binding unique keys to
values (which are not necessarily unique), though it can not guarantee
consistent order its elements when iterating. Because of the nature of
Hash adds a number of
methods that let you enumerate keys and values, iterate over key/value
pairs, merge two hashes together, and much more.
Creating a hash
There are two ways to construct a Hash instance: the first is regular
new keyword, and the second is
$H function. There is one difference between them: if a
is passed to
$H, it will be returned as-is, wherease the same hash passed
new Hash will be cloned instead.