A **Fibonacci** Word is a specific sequence of binary digits (or symbols from any two-letter alphabet). The Fibonacci Word is formed by repeated concatenation in the same way that the Fibonacci numbers are formed by repeated addition.
Create a **function** that takes a number **n** as an argument and returns the first **n** elements of the Fibonacci Word sequence.
If **n < 2**, the function must return "**invalid**". **Examples**

FiboWord(1) ➞ "invalid"

FiboWord(3) ➞ "b, a, ab"

FiboWord(7) ➞ "b, a, ab, aba, abaab, abaababa, abaababaabaab"

**Notes**
You can try solving this using a recursive approach.

**Resources**
[Fibonacci Number](https://en.wikipedia.org/wiki/Fibonacci_sequence)
[Fibonacci word](https://en.wikipedia.org/wiki/Fibonacci_word)