docs: 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))