code: def expected_duration(self, expected_duration):
          
  
          if expected_duration is None:
              raise ValueError("Invalid value for `expected_duration`, must not be `None`")
          if len(expected_duration) < 1:
              raise ValueError("Invalid value for `expected_duration`, length must be greater than or equal to `1`")
  
          self._expected_duration = expected_duration
docs: Sets the expected_duration of this ModelBreak.
          Format: RFC-3339 P[n]Y[n]M[n]DT[n]H[n]M[n]S. The expected length of the break.
  
          :param expected_duration: The expected_duration of this ModelBreak.
          :type: str