Add an `expand` transform

[ahuang11]

It might already exist, but I'm just trying to subset the KCMI column before it becomes a DataFrame

sources:
  aviation_source:
    type: json
    tables:
      kcmi_chart: https://api.aviationapi.com/v1/charts?apt=KCMI
 
layouts:
  - title: Aviation
    source: aviation_source
    views:
      - type: hvplot_ui
        table: kcmi_chart

Like

import requests
import pandas as pd
pd.DataFrame.from_records(requests.get("https://api.aviationapi.com/v1/airports?apt=KCMI").json()["KCMI"])