Consultation on modifying all unit costs

a) Hello, since BioSTEAM does not have ```Chinese investment_site_factors``` (https://biosteam.readthedocs.io/en/latest/API/TEA.html#:~:text=investment_site_factors%3A%20dict%5Bstr%2C%20float%5D%20%3D%20%7B%27India%27%3A%200.85%2C%20%27Japan%27%3A%201.15%2C%20%27Mexico%27%3A%200.95%2C%20%27Pacific%20Rim%27%3A%201.0%2C%20%27U.S.%20Gulf%20Coast%27%3A%201.0%2C%20%27U.S.%20Midwest%27%3A%201.15%2C%20%27U.S.%20Northwest%27%3A%201.1%2C%20%27U.S.%20Southwest%27%3A%200.95%2C%20%27U.S.%20West%20Coast%27%3A%201.25%2C%20%27Western%20Europe%27%3A%201.2%7D), may I ask you how to call ```investment_site_factors``` when executing TEA and how to call ```Chinese investment_site_factors (0.83)``` when executing TEA ? Because I didn't find any tutorials for ```investment_site_factors```.

b) Or I can modify the unit cost according to the tutorial in ```TAL``` model (https://github.com/agvaughan/Bioindustrial-Park/blob/8ce1740633fac93821137019eaec11be0f5d94a2/biorefineries/TAL/analyses/models_ethyl_esters.py#L194-L200), but I can only change the cost of some units through the following code (only the unit with cost_items), could I consult you how to modify the cost of all units in the system?
```
from biorefineries import TAL
import biosteam as bst
bst.nbtutorial()
TAL.load_TAL_model('A')
TAL.system.diagram('thorough', format='png', number=True)
for unit in TAL.system.units:
if hasattr(unit, 'cost_items'):
print(unit)
```