Add more methods to SINumber

[marcosfelt]

Thanks for this package! The SINumber wrapper in python does not seem to have the same methods as the equivalent object in rust (see here). For example, I cannot call .value on a SINumber. Would it be possible to add that functionality? Below is an example:

from feos.si import *
T = 300*KELVIN
T.value

AttributeError                            Traceback (most recent call last)
[<ipython-input-55-7f7315c6633b>](https://localhost:8080/#) in <module>
      1 from feos.si import *
      2 T = 300*KELVIN
----> 3 T.value

AttributeError: 'si_units.SINumber' object has no attribute 'value'

[g-bauer]

Hey, thanks for your interest in FeOs.

You can get a float (or an array of floats) by dividing by the unit, i.e. in your example T / KELVIN would result in 300.0. Of course, that only works if the units cancel out. In Rust with static data types we have to convert a "dimensionless" quantity, and that's where e.g. value can be used.

I don't think value is needed in Python - when performing arithmetic operations that cancel units, we automatically return the underlying data (float or array of floats).

Let me know if that helps!

[marcosfelt]

That does! Thank you!!

[g-bauer]

Great! If you encounter more problems regarding the unit system, there is a tutorial in our documentation.