text: def modify(gas,cloud,C,Cl):
  
      comment = "Uranus tweaking"
      
      nAtm = len(gas[C['P']])
      for i in range(nAtm):
          Plyr = gas[C['P']][i]
          Tlyr = gas[C['T']][i]
          
          ### Process H2S
  
  
          ### Process NH3 
  
  
          ### Process CO
          gas[C['CO']][i] = 0.0
          ### Process CO13
          gas[C['CO13']][i] = 1.0E-2*gas[C['CO']][i]
          ### Process HCN, SOLN, PH3
          gas[C['HCN']][i] = 0.0
          gas[C['SOLN']][i] = 0.0
          gas[C['PH3']][i] = 0.0
  
      return comment, gas, cloud
  