Append data to a table or chart
In Streamlit, you can not only replace entire elements in your app, but also
modify the data behind those elements. Here is how:
```python
import numpy as np
import time
Get some data.
data = np.random.randn(10, 2)
Show the data as a chart.
chart = st.line_chart(data)
Wait 1 second, so the change is clearer.
time.sleep(1)
Grab some more data.
data2 = np.random.randn(10, 2)
Append the new data to the existing chart.
chart.add_rows(data2)
```
