Use checkboxes to show/hide data
One use case for checkboxes is to hide or show a specific chart or section in
an app. st.checkbox() takes a single argument,
which is the widget label. In this sample, the checkbox is used to toggle a
conditional statement.
```python
import streamlit as st
import numpy as np
import pandas as pd
if st.checkbox('Show dataframe'):
    chart_data = pd.DataFrame(
       np.random.randn(20, 3),
       columns=['a', 'b', 'c'])
chart_data
```
Use a selectbox for options
Use st.selectbox to choose from a series. You
can write in the options you want, or pass through an array or data frame
column.
Let's use the df data frame we created earlier.
```python
import streamlit as st
import pandas as pd
df = pd.DataFrame({
    'first column': [1, 2, 3, 4],
    'second column': [10, 20, 30, 40]
