Add a global parameter to the database that can be accessed by functions

def add_parameter(self, param_name, description=None, default=0, unit=None):
        """
        Add a global parameter to the database that can be accessed by functions
        """

        if description is None:
            description = "Parameter called {}".format(param_name)

        if unit is None:
            unit = "-"
        
        name_check = lambda x: x['name'] == param_name
        name_check_list = list(filter(name_check, self.ext_params))
        if len(name_check_list) == 0:
            self.ext_params.append({'name': param_name, 'description': description, 'default': default, 'unit': unit})
        else:
            print('{} already exists - choose a different name'.format(param_name))