Flexible method to get any data using the Materials Project REST
        interface. Generally used by other methods for more specific queries.
        Unlike the :func:`get_data`_, this method queries the task collection
        for specific run information.

        Format of REST return is *always* a list of dict (regardless of the
        number of pieces of data returned. The general format is as follows:

        [{"material_id": material_id, "property_name" : value}, ...]

        Args:
            chemsys_formula_id (str): A chemical system (e.g., Li-Fe-O),
                or formula (e.g., Fe2O3) or materials_id (e.g., mp-1234).
            prop (str): Property to be obtained. Should be one of the
                MPRester.supported_properties. Leave as empty string for a
                general list of useful properties.

def get_task_data(self, chemsys_formula_id, prop=""):
        """
        Flexible method to get any data using the Materials Project REST
        interface. Generally used by other methods for more specific queries.
        Unlike the :func:`get_data`_, this method queries the task collection
        for specific run information.

        Format of REST return is *always* a list of dict (regardless of the
        number of pieces of data returned. The general format is as follows:

        [{"material_id": material_id, "property_name" : value}, ...]

        Args:
            chemsys_formula_id (str): A chemical system (e.g., Li-Fe-O),
                or formula (e.g., Fe2O3) or materials_id (e.g., mp-1234).
            prop (str): Property to be obtained. Should be one of the
                MPRester.supported_properties. Leave as empty string for a
                general list of useful properties.
        """
        sub_url = "/tasks/%s" % chemsys_formula_id
        if prop:
            sub_url += "/" + prop
        return self._make_request(sub_url)