old_contents: # Merge addresses into buildings they intersect with
  
  from fiona import collection
  from rtree import index
  from shapely.geometry import asShape, Point, LineString
  
  def merge(buildingIn, addressIn):
      addresses = []
  
      with collection(addressIn, "r") as input:
          for address in input:
              shape = asShape(address['geometry'])
              shape.original = address
              addresses.append(shape)
  
      # Load and index all buildings.
      buildingIdx = index.Index()
      buildings = []
      with collection(buildingIn, "r") as input:
          for building in input:
              building['shape'] = asShape(building['geometry'])
              building['properties']['addresses'] = []
              buildings.append(building)
              buildingIdx.add(len(buildings) - 1, building['shape'].bounds)
  
      # Map addresses to buildings.
      for address in addresses:
          for i in buildingIdx.intersection(address.bounds):
              if buildings[i]['shape'].contains(address):
                  buildings[i]['properties']['addresses'].append(
                      address.original)
  
      return {
          'buildings': buildings,
          'index': buildingIdx
      }
  
new_contents: # Merge addresses into buildings they intersect with
  from fiona import collection
  from rtree import index
  from shapely.geometry import asShape, Point, LineString
  
  def merge(buildingIn, addressIn):
      addresses = []
  
      with collection(addressIn, "r") as input:
          for address in input:
              shape = asShape(address['geometry'])
              shape.original = address
              addresses.append(shape)
  
      # Load and index all buildings.
      buildingIdx = index.Index()
      buildings = []
      with collection(buildingIn, "r") as input:
          for building in input:
              building['shape'] = asShape(building['geometry'])
              building['properties']['addresses'] = []
              buildings.append(building)
              buildingIdx.add(len(buildings) - 1, building['shape'].bounds)
  
      # Map addresses to buildings.
      for address in addresses:
          for i in buildingIdx.intersection(address.bounds):
              if buildings[i]['shape'].contains(address):
                  buildings[i]['properties']['addresses'].append(
                      address.original)
  
      return {
          'buildings': buildings,
          'index': buildingIdx
      }
  
subject: Remove whitespace.