import xlwings as xw

@xw.func
@xw.arg('x', xw.Range)
@xw.arg('y',xw.Range)
@xw.arg('z',xw.Range)
@xw.ret(expand = "vertical")
def calc_scenario(x,y, z):
    address = x.address
    formula = x.formula

    res = []
    for scenario in y.value:
        x.value = scenario
        res.append(z.value)

    x.formula = formula

    return res

import xlwings as xw

sht = xw.Book("TestStuff.xlsm").sheets[0]

def calc_scenario(x,y, z):
    address = x.address
    formula = x.formula

    res = []
    for scenario in y.value:
        x.value = scenario
        res.append(z.value)

    x.formula = formula

    return res

x = sht.range("C43:H43")
y = sht.range("C47:H49")
z = sht.range("C45")
calc_scenario(x,y,z)