code: def dr_hill_zero_background(x, theta, eta, kappa):
      
      return (theta* x**eta) / (kappa**eta + x**eta)
docs: dr hill zero background
   
      Parameters
      ----------
      x: int
      theta: float
      eta: float
      kappa: float
  
      Returns
      -------
      float
          (theta* x**eta) / (kappa**eta + x**eta)