def sample(self):
        """
        This is the core sampling method. Samples a state from a
        demonstration, in accordance with the configuration.
        """

        # chooses a sampling scheme randomly based on the mixing ratios
        seed = random.uniform(0, 1)
        ratio = np.cumsum(self.scheme_ratios)
        ratio = ratio > seed
        for i, v in enumerate(ratio):
            if v:
                break

        sample_method = getattr(self, self.sample_method_dict[self.sampling_schemes[i]])
        return sample_method()
This is the core sampling method. Samples a state from a
        demonstration, in accordance with the configuration.