def add(self, key, vals, shorthand=None, in_name=False):
        """
        Add a parameter (key) to the grid config, with potential values (vals).

        By default, if a shorthand isn't given, one is automatically generated
        from the key using the first three letters of each colon-separated
        term. To disable this behavior, change ``DEFAULT_SHORTHAND`` in the
        ``spinup/user_config.py`` file to ``False``. 

        Args:
            key (string): Name of parameter.

            vals (value or list of values): Allowed values of parameter.

            shorthand (string): Optional, shortened name of parameter. For 
                example, maybe the parameter ``steps_per_epoch`` is shortened
                to ``steps``. 

            in_name (bool): When constructing variant names, force the
                inclusion of this parameter into the name.
        """
        assert isinstance(key, str), "Key must be a string."
        assert shorthand is None or isinstance(shorthand, str), \
            "Shorthand must be a string."
        if not isinstance(vals, list):
            vals = [vals]
        if DEFAULT_SHORTHAND and shorthand is None:
            shorthand = self._default_shorthand(key)
        self.keys.append(key)
        self.vals.append(vals)
        self.shs.append(shorthand)
        self.in_names.append(in_name)

        Add a parameter (key) to the grid config, with potential values (vals).

        By default, if a shorthand isn't given, one is automatically generated
        from the key using the first three letters of each colon-separated
        term. To disable this behavior, change ``DEFAULT_SHORTHAND`` in the
        ``spinup/user_config.py`` file to ``False``. 

        Args:
            key (string): Name of parameter.

            vals (value or list of values): Allowed values of parameter.

            shorthand (string): Optional, shortened name of parameter. For 
                example, maybe the parameter ``steps_per_epoch`` is shortened
                to ``steps``. 

            in_name (bool): When constructing variant names, force the
                inclusion of this parameter into the name.
        
spinup/utils/run_utils.py