code: def rel_humid_from_db_enth(db_temp, enthalpy, b_press=101325):
      
      assert enthalpy >= 0, 'enthalpy must be' \
          'greater than 0. Got {}'.format(str(enthalpy))
      hr = (enthalpy - (1.006 * db_temp)) / ((1.84 * db_temp) + 2501)
      rel_humid = rel_humid_from_db_hr(db_temp, hr, b_press)
      return rel_humid
docs: Relative Humidity (%) at db_temp (C), enthalpy (kJ/kg)
      and Pressure b_press (Pa).