Do you know how to check if the given year is a leap year or not?
Let us go through a simple leap year code snippet.

The above code snippets read like:
If a given year is divisible by 4, 100, and 400 then given number is a leap year.
If a given year is divisible by 4 and 100 but it is not divisible by 400 then it is NOT a leap year.
If a given year is divisible by 4, but it is NOT divisible by 100 then it is a leap year.
Otherwise given number is NOT a leap year.
Did you realize that readability is poor when you use deeply nested conditionals?
Even a simple program becomes difficult to understand.
This is called Arrow anti-pattern because too many nested if represent an arrow-like shape.)
Readability could be achieved by returning as early as possible.
Let’s see via example.

Don’t you think the second one is easier to understand?
It reads like
If a given year is divisible by 400 then it’s a leap year.
Otherwise if divisible by 100 then it’s NOT a leap year.
Otherwise if divisible by 4 then it’s a leap year.
Oherwise it’s NOT a leap year.