docs: def serialize_quantity(o):
      """
      Serializes an :obj:`astropy.units.Quantity`, for JSONification.
  
      Args:
          o (:obj:`astropy.units.Quantity`): :obj:`Quantity` to be serialized.
  
      Returns:
          A dictionary that can be passed to :obj:`json.dumps`.
      """
      return dict(
          _type='astropy.units.Quantity',
          value=o.value,
          unit=o.unit.to_string())