Fetch some data
Now that you have an app, the next thing you'll need to do is fetch the Uber
dataset for pickups and drop-offs in New York City.
Let's start by writing a function to load the data. Add this code to your
   script:
```python
   DATE_COLUMN = 'date/time'
   DATA_URL = ('https://s3-us-west-2.amazonaws.com/'
            'streamlit-demo-data/uber-raw-data-sep14.csv.gz')
def load_data(nrows):
       data = pd.read_csv(DATA_URL, nrows=nrows)
       lowercase = lambda x: str(x).lower()
       data.rename(lowercase, axis='columns', inplace=True)
       data[DATE_COLUMN] = pd.to_datetime(data[DATE_COLUMN])
       return data
   ```
You'll notice that load_data is a plain old function that downloads some
   data, puts it in a Pandas dataframe, and converts the date column from text
   to datetime. The function accepts a single parameter (nrows), which
