Example Mismatch

Python example to compress a string with snappy can't be decompressed with the command line tool example to decompress a file with the same string in it. The command line tool should be expanded to support this use case, or at the very least a second programmatic example explaining how to create a file which can be read with the tool.

```
import snappy
import os
fout = open('compressed_file.snappy', 'w')
buf ='hello world'
buf = snappy.compress(buf)
fout.write(buf)
fout.close()
os.system("python -m snappy -d compressed_file.snappy uncompressed_file");
```

UncompressError: chunk truncated

Start with the Python compression example and the `python -m snappy -d compressed_file.snappy uncompressed_file` entry point, reproducing the reported `UncompressError: chunk truncated`. Determine whether the command-line tool should support this output or whether a second programmatic example is needed; done means the chosen path works consistently and is documented.

索引モデルが issue の本文から書いたものです。