index.rb

class Account
  attr_reader :owner
  def initialize(owner: nil) 
    @owner = owner
  end 
end 

# we can safely try to access the address even without risk of getting a nil error

# this first example throws an error

account = Account.new
p account.owner.address
# # error

# this is how we used to have to write ruby code to avoid the nil error

p account && account.owner && account.owner.address
# # => nil 

# this is a more elequent way of writing the above

p account&.owner&.address
# => nil 

# keyword arguments have a couple of advantages
# firstly you can use an identifer for an argument that you pass, or in other words you give it a name
# secondly you can pass the arguments in any order you like
# thirdly you can assign default values in your method parameters to avoid argument errors

def my_method(num_2: 0, num_1: 0) 
  num_1 + num_2
end 

p my_method(num_2: 3)