method
hash
hash()
protected
Generates an Integer hash value for this object. This function must have the property that a.eql?(b) implies a.hash == b.hash.
The hash value is used along with #eql? by the Hash class to determine if two objects reference the same hash key. Any hash value that exceeds the capacity of an Integer will be truncated before being used.
The hash value for an object may not be identical across invocations or implementations of Ruby. If you need a stable identifier across Ruby invocations and implementations you will need to generate one with a custom method.