Return summary statistics of a column as JSON.
    Uses Pandas' "split" JSON format.

def column_describe(table_name, col_name):
    """
    Return summary statistics of a column as JSON.
    Uses Pandas' "split" JSON format.

    """
    col_desc = orca.get_table(table_name).get_column(col_name).describe()
    return (
        col_desc.to_json(orient='split'),
        200,
        {'Content-Type': 'application/json'})