本系列主要用于自我学习，参考的为bubbliiiing的代码

写一个优雅的：从txt文件中获得类别名与类别数的函数，如下：

#---------------------------------------------------#
#   获得类别名与类别数
#---------------------------------------------------#
def get_classes(classes_path):
    with open(classes_path, encoding='utf-8') as f:
        class_names = f.readlines()
    class_names = [c.strip() for c in class_names]
    return class_names, len(class_names)


if __name__ == "__main__":
	classes_path = 'model_data/voc_classes.txt'
	class_names, num_classes = get_classes(classes_path)