derive Enumerable

[gemmaro]

Since the each method is already defined, we may include the Enumerable module.
Then the following methods will be derived:

irb(main):007:0> ndjson = NDJSON::Parser.new('sample.ndjson')
=> #<NDJSON::Parser:0x000000010535d058 @input=#<File:sample.ndjson>>
irb(main):008:0> ndjson.first
=> {"some"=>"thing"}
irb(main):009:0> ndjson.find { _1.size == 3 }
=> {"foo"=>17, "bar"=>false, "quux"=>true}