code: def E_CMFR_N(t, N):
      
      return (N**N)/special.gamma(N) * (t**(N-1))*np.exp(-N*t)
docs: Calculate a dimensionless measure of the output tracer concentration
      from a spike input to a series of completely mixed flow reactors.
  
      :param t: The time(s) at which to calculate the effluent concentration. Time can be made dimensionless by dividing by the residence time of the CMFR.
      :type t: float or numpy.array
      :param N: The number of completely mixed flow reactors (CMFRS) in series. Must be greater than 1.
      :type N: int
  
      :return: Dimensionless measure of the output tracer concentration (concentration * volume of 1 CMFR) / (mass of tracer)
      :rtype: float
  
      :Examples:
  
      >>> from aguaclara.research.environmental_processes_analysis import E_CMFR_N
      >>> round(E_CMFR_N(0.5, 3), 7)
      0.7530643
      >>> round(E_CMFR_N(0.1, 1), 7)
      0.9048374