code: def from_dict(cls, parameters):
          
          instance = cls()
          instance.fitted = parameters['fitted']
          instance.constant_value = parameters['constant_value']
  
          if instance.fitted and instance.constant_value is None:
              instance.model = scipy.stats.truncnorm(parameters['a'], parameters['b'])
  
          return instance
docs: Set attributes with provided values.
  
          Args:
              parameters(dict): Dictionary containing instance parameters.
  
          Returns:
              Truncnorm: Instance populated with given parameters.