new_contents: """ Created by Max Robinson 9/20/2017 """
  
  
  class SFS:
      pass
  
  
  """
  Pseudo code
  
  function SFS(Features, D_train, D_valid, Learn()): 
      F_0 = <>
      basePerf = -inf
      do:
          bestPerf = - inf
          for all Features in FeatureSpace do: 
              F_0 = F_0 + F
              h = Learn(F_0, D_train)
              currPerf = Perf(h, D_valid)
              if currPerf > bestPerf then:
                  bestPerf = currPerf
                  bestF = F
              end if
              F_0 = F_0 - F
          end for
          if bestPerf > basePerf then 
              basePerf = bestPerf
              F = F - bestF 
              F_0 = F_0 + bestF
          else
              exit (Break)
          end if
      until F = <> (is empty)
      return F_0
  
  """
subject: Add skeleton for SFS algorithm