说明
生成歌曲《I Know an Old Lady Who Swallowed a Fly》的歌词。
你当然可以复制粘贴歌词，或者从文件里读取，但如果用算法的方式来解决，这道题会有趣得多。
这是一首来源不明的累积歌曲。
这是众多常见版本之一。
I know an old lady who swallowed a fly.
I don't know why she swallowed the fly. Perhaps she'll die.
I know an old lady who swallowed a spider.
It wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.
I know an old lady who swallowed a bird.
How absurd to swallow a bird!
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.
I know an old lady who swallowed a cat.
Imagine that, to swallow a cat!
She swallowed the cat to catch the bird.
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.
I know an old lady who swallowed a dog.
What a hog, to swallow a dog!
She swallowed the dog to catch the cat.
She swallowed the cat to catch the bird.
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.
I know an old lady who swallowed a goat.
Just opened her throat and swallowed a goat!
She swallowed the goat to catch the dog.
She swallowed the dog to catch the cat.
She swallowed the cat to catch the bird.
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.
I know an old lady who swallowed a cow.
I don't know how she swallowed a cow!
She swallowed the cow to catch the goat.
She swallowed the goat to catch the dog.
She swallowed the dog to catch the cat.
She swallowed the cat to catch the bird.
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.
I know an old lady who swallowed a horse.
She's dead, of course!
Wren 中的方法签名
在 wren 中，你可以_按参数数量_重载方法。
这意味着，只要方法接受的实参数量不同，你的类就可以有两个（或更多）同名方法。
更多细节请参见签名。
