code: def force_symmetric(self):
          
          if self.offset != 0.:
              raise RuntimeError(
                      'Laminates with offset cannot be forced symmetric!')
          self.B = np.zeros((3,3))
          self.ABD[0:3, 3:6] = 0
          self.ABD[3:6, 0:3] = 0
  
          self.ABDE[0:3, 3:6] = 0
          self.ABDE[3:6, 0:3] = 0
docs: Force a symmetric laminate
  
          The `B` terms of the constitutive matrix are set to zero.