Function [_select_buildings()](https://github.com/UDST/developer/blob/master/developer/develop.py#L407) fails when `self.target_units` is a `pd.DataFrame`. While in the first lines checks for the `target_units` type, then [it gets used in followings functions disregarding it](_select_buildings()).
Function _select_buildings() fails when
self.target_unitsis apd.DataFrame. While in the first lines checks for thetarget_unitstype, then it gets used in followings functions disregarding it.