GERG-2008 flash calculation

[qingqi-code]

Hi, I am working to use GERG-2008 to calculate flash model. I have a question about the density calculation.
The code

            if T and P:
                rhoo = 2.
                rho = fsolve(lambda rho: self._solve(rho, T)["P"]-P*1e6, rhoo)

seems need manually guess a density. However, if the guess is too far away from the root, the code can not run successfully. So I am wondering when it comes to phase envelope calculation, how can I manually change the guess figure? Can you modify this part? Thank you so much!