In Ruby it is possible to send a Hash as an argument to a method.

Suppose we have a method named conversion_method which has 4 default parameters(a,b,c,d). ex:-

2.1.5 :086 >   def conversion_method(a:10, b:20, c:30, d:40)
2.1.5 :087?>   puts "a = " + a.to_s + " b = " + b.to_s + " c = " + c.to_s + " d = " + d.to_s
2.1.5 :088?>   end 

And we have a Hash with 4 key-value pairs , ex:-

2.1.5 :096 > arguments = { a: 100, b: 200, c: 300, d: 400 }
 => {:a=>100, :b=>200, :c=>300, :d=>400}

You can verify that arguments is a Hash.

2.1.5 :098 > arguments.class
 => Hash

Now if we wish to send this Hash to the conversion_method function we can send it as follows

2.1.5 :100 > conversion_method(**arguments)
a = 100 b = 200 c = 300 d = 400