2022-10: Separation Anxiety

Write code that:

- takes a second argument that is a character vector or scalar representing a valid non-negative integer.

- takes a first argument that is a character scalar "separator" character.

- returns a character vector that is a representation of the second argument formatted such that the separator character is found between trailing groups of 3 digits.

- Note that the number of digits in the character representation might exceed the number of digits that can be represented as a 32-bit integer.