Show progress
When adding long running computations to an app, you can use
st.progress() to display status in real time.
First, let's import time. We're going to use the time.sleep() method to
simulate a long running computation:
python
import time
Now, let's create a progress bar:
```python
import streamlit as st
import time
'Starting a long computation...'
Add a placeholder
latest_iteration = st.empty()
bar = st.progress(0)
for i in range(100):
  # Update the progress bar with each iteration.
  latest_iteration.text(f'Iteration {i+1}')
  bar.progress(i + 1)
  time.sleep(0.1)
'...and now we\'re done!'
```
Themes
Streamlit supports Light and Dark themes out of the box. Streamlit will first
check if the user viewing an app has a Light or Dark mode preference set by
their operating system and browser. If so, then that preference will be used.
