Ruby Safenavigationoperatorapple&.color

refer to:
https://stackoverflow.com/questions/36812647/what-does-ampersand-dot-mean-in-ruby

class Apple 
    attr_accessor :color
end

apple = Apple.new color: 'red'
apple&.color # => red
b = nil
b&.color #=> nil

所以， &.  就相当于 rails 中的try