Modeler.set_variable doesn't work in python shell (I have the solution)

[AdrienGuimbal]

In HFSSdrawpy.core.modeler.Modeler.set_variable, the "hack" to auto-name variables assumes the python code lives inside a file, so when the code is tested inside a shell, an error occcures.
The error message is

File "........\modeler.py", line 79, in set_variable
code_line = open(filename).readlines()[f.f_lineno - 1]

Which isn't very usefull

I suggest the following changes for the function Modeler.set_variable

    def set_variable(self, value, name=None):
        """
        name (str): name of the variable in HFSS e.g. 'chip_length', only optionnal if used inside a .py script
        value (str, VarStr, float): value of the variable
                                    if str will try to analyse the unit
        """

        if name is None:
            # this auto-parsing is clearly a hack and not robust
            # but I find it convenient
            f = currentframe().f_back  # .f_back
            filename = getfile(f)
            if filename != '<stdin>':
                code_line = open(filename).readlines()[f.f_lineno - 1]
                name = code_line.split("=")[0].strip()
            else:
                raise ValueError("Please provide a name for the variable, automatic naming only works in .py scripts")

        if self.mode == "hfss":
            self.design.set_variable(name, value)  # for HFSS
        symbol = sympy.symbols(name)
        store_variable(symbol, value)
        return symbol

Adding just an if statement and corecting the documentation

I didn't made tests for .ipynb, I'll leave it to whoever has the time to do it (I dont have a setup for this)

Thanks to whoever take the time to correct this minor issue

Acknowledgement : this is more a Pull Request than an open issue, but I don't have the permission to create a branch and I'm not very fluent with Giuhub (for yet ?)

[AdrienGuimbal]

I just thought about an other problem :
The code whould send an error if the left-hand side contains a comma
otherwise a, b = set_variable("1mm"), set_variable("2mm") will be equivalent to a, b = set_variable("1mm", "a, b"), set_variable("2mm", "a, b") instead of a, b = set_variable("1mm", "a"), set_variable("2mm", "a")

[AdrienGuimbal]

It also doen't play nicely with walrus operator. I suggest an error to be raised if the line doesn't coply with the scheme <whitespace>varname<whitespace>=<whitespace>funcname(<whatever well parenthesised>)<whitespace><optional comment>