code: def Henry_H_at_T(T, H, Tderiv, T0=None, units=None, backend=None):
      
      be = get_backend(backend)
      if units is None:
          K = 1
      else:
          K = units.Kelvin
      if T0 is None:
          T0 = 298.15*K
      return H * be.exp(Tderiv*(1/T - 1/T0))
docs: Evaluate Henry's constant H at temperature T
  
      Parameters
      ----------
      T: float
          Temperature (with units), assumed to be in Kelvin if ``units == None``
      H: float
          Henry's constant
      Tderiv: float (optional)
          dln(H)/d(1/T), assumed to be in Kelvin if ``units == None``.
      T0: float
          Reference temperature, assumed to be in Kelvin if ``units == None``
          default: 298.15 K
      units: object (optional)
          object with attributes: kelvin (e.g. chempy.units.default_units)
      backend : module (optional)
          module with "exp", default: numpy, math