Incorrect signature for BMI initialize method

[mcflugen]

According to the BMI spec, the filename argument for the BMI initialize method must not be optional and must be a string. Right now BmiHeat.initialize accepts either None, a file-like object, or a string. I think this should be changed so that it only accepts a string that is a path to a configuration file.

i.e.

def initialize(self, filename: str):
    with open(filename) as file_obj:
        self._model = Heat.from_file_like(file_obj)
    ...

Actually, in looking at what's there now, I think there's also a bug. Heat.from_file_like must take a stream, not a string

i.e.

Heat.from_file_like(file_obj.read())

should be

Heat.from_file_like(file_obj)

[mcflugen]

I think it would be safe to use the empty string to indicate a default configuration.

def initialize(self, filename: str):
    if filename:
        with open(filename) as file_obj:
            self._model = Heat.from_file_like(file_obj)
    else:
        self._model = Heat()
    ...