text: class Product:
      def __init__(self,psi,ksi):
          import numpy as np
          self.ksi=ksi
          self.psi=psi
  
      def Tech(self,FacDemand,sign=1.0):
          '''This is simply the technology function.'''
          import numpy as np
          FacDemand=np.array(FacDemand,dtype=float)
          return sign*(np.dot(self.psi,np.power(FacDemand,(1.0-self.ksi))/(1.0-self.ksi)))
  