By putting `load()` as a static function for `GA`, the usage of this nice library could be more concise

```Python
from pygad import GA

def fitness_func(solution):
    return fitness_value

ga = GA(
    # ...
)

ga.run()
ga.plot_result()
best_solution, best_solution_fitness = ga.best_solution()
print(f'Best solution:, {best_solution}')
print(f'Fitness value of the best solution: {best_solution_fitness}')
ga.save(filename)
```