With new pandas:
pd.Index([])|pd.MultiIndex(...)
returns a pd.Index, not a pd.MultiIndex, so just reversed:
pd.MultiIndex(...)|pd.Index([])
This returns a pd.MultiIndex.
Heat buses renamed to:
rural (for low-density areas where district heating not possible)
urban decentral (for high-density areas without district heating and
individual heating technologies) (used to be called "urban")
urban central (for high-density areas with district heating) (used to
be called "central")
District heating losses applied only to urban central.
