explain `e = (1..3).chain([4, 5]) e.to_a #=> [1, 2, 3, 4, 5]` in ruby

In Ruby, the chain method allows you to concatenate two enumerables together. When you call chain on an enumerable, it returns a new enumerator that iterates over the elements of the original enumerable followed by the elements of another enumerable.

Let's break down the code example you provided:

main.rb
e = (1..3).chain([4, 5])
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Here, we have an enumerator e that is created by chaining the range (1..3) with the array [4, 5]. The range (1..3) represents the integers from 1 to 3, and the array [4, 5] contains the elements 4 and 5.

main.rb
e.to_a #=> [1, 2, 3, 4, 5]
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Calling to_a on the enumerator e converts it into an array. The resulting array [1, 2, 3, 4, 5] contains all the elements from the original range (1..3) followed by the elements from the array [4, 5].

In summary, the chain method allows you to combine multiple enumerables into one enumerator, and calling to_a on that enumerator converts it into an array with all the elements in the concatenated order.