input: Write a python function to calculate the fitness score for a given population and expression.
  assert fitness(lambda x: x**2 - 3*x - 10, [1, 2, 3, 4, 5])==[-12, -9, -8, -9, -12]
  assert fitness(lambda x: x**2 - 3*x - 10, [-10, -5, 0, 5, 10])==[-130, -60, -10, -10, 60]
  assert fitness(lambda x: x**2 - 3*x - 10, [0, 0, 0])==[-10, -10, -10]
output: def fitness(expression, population):
      return [expression(individual) for individual in population]