I have a shapefile that contains 200+ metropolitan cities. In each city, there are some tract polygons. The dbf table looks like:

```
tract  city    xvar
1      0040    20
2      0040    12
3      0040    45
...    ...     ...
5      5602    22
6      5602    44
...    ...     ...

```

My goal is to select a city and save it as a separate shapefile the name of which is the same as the city code:

**0040.shp**

```
tract  city    xvar
1      0040    20
2      0040    12
3      0040    45
...    ...     ...

```

**5602.shp**

```
tract  city    xvar
5      5602    22
6      5602    44
...    ...     ...

```

How should I automate this process for all the cities using arcpy?