Quadratic Formula

Write a program quadratic_formula.py that determines solutions to a quadratic equation. The main program has the user enter three coefficients for a quadratic formula of the form ax² + bx + c = 0. The program then calls a function get_solutions which

1. takes a, b, and c as parameters
2. calculates the discriminant disc = b^2 - 4 * a * c
3. returns one of three values:
   1. A pair of solutions (separated by a comma) if the discriminant > 0
   2. The single solution if the discriminant = 0
   3. The value None if the discriminant is < 0