without-the-letter-e

Without the letter 'E'

Is it possible to write a book without the letter 'e' ?

Given String str, return:

• How many "e" does it contain (case-insensitive) in string format.
• If given String doesn't contain any "e", return: "There is no "e"."
• If given String is empty, return empty String.
• If given String is null/None/nil, return null/None/nil