old_contents: from __future__ import absolute_import
  
  
  class Source(object):
      "Parent class for sources"
  
      def __init__(self, query, bounds=None):
          self.query = query
          self.bounds = bounds
  
new_contents: from __future__ import absolute_import
  
  
  class Source(object):
      """Data source. Parent class for CARTO VL related source types:
        - :py:class:`SQL <cartoframes.carto_vl.source.SQL>`.
        - :py:class:`Dataset <cartoframes.carto_vl.source.Dataset>`.
        - :py:class:`GeoJSON <cartoframes.carto_vl.source.GeoJSON>`.
  
        Args:
          - query (str, GeoDataFrame): Source query for the data.
          - bounds (dict): Viewport bounds.
      """
  
      def __init__(self, query, bounds=None):
          self.query = query
          self.bounds = bounds
  
subject: Add docs to source