# creating an empty hash
h = {} # => {}
h["a"] = 1 # => {"a" => 1}
h["test"] = 2.4 # => {"a" => 1, "test" => 2.4}
h[3] = "Hello" # => {"a" => 1, "test" => 2.4, 3 => "Hello"}
# creating a hash with the constructor
h = Hash.new # => {}