def load(self, filename, create_if_missing=True):
        filename = Path(filename)
        if not filename.exists() and create_if_missing:
            self.load_pip_requirements()
            with filename.open("w") as f:
                f.write(yaml.dump(self.serialized, default_flow_style=False,
                                  encoding=None))
            self.filename = filename
            return self.save(filename)
        with filename.open() as f:
            for group, requirements in yaml.load(f.read()).items():
                for requirement in requirements:
                    self[group].add(Requirement.coerce(requirement))
        self.filename = filename
def __init__(self, cost_withGradients):
        super(CostModel, self).__init__()

        self.cost_type = cost_withGradients

        # --- Set-up evaluation cost
        if self.cost_type is None:
            self.cost_withGradients = constant_cost_withGradients
            self.cost_type = 'Constant cost'

        elif self.cost_type == 'evaluation_time':
            self.cost_model = GPModel()
            self.cost_withGradients = self._cost_gp_withGradients
            self.num_updates = 0
        else:
            self.cost_withGradients = cost_withGradients
            self.cost_type = 'User defined cost'