describe this: ([*'a'..'z'] - phrase.downcase.chars).empty? in ruby

The given code is written in Ruby and it checks whether a given phrase contains all the letters from the English alphabet.

Here is a step-by-step explanation of the code:

1. phrase.downcase.chars: This converts the given phrase string to lowercase and then splits it into an array of characters.

2. [*'a'..'z']: This creates an array containing all the lowercase letters from 'a' to 'z'.

3. ([*'a'..'z'] - phrase.downcase.chars): This performs an array subtraction operation, where it subtracts the array of characters in phrase from the array of all lowercase letters. This gives us an array of letters that are present in the English alphabet but not in the phrase.

4. .empty?: This checks if the resulting array from the subtraction operation is empty or not. If it is empty, it means that the phrase contains all the letters from 'a' to 'z'.

So, in summary, the code determines if a given phrase contains all the lowercase letters from 'a' to 'z'. If it does, the expression will evaluate to true. Otherwise, it will evaluate to false.

Tags: ruby, string manipulation, array manipulation