code: def QUANTILE(src_column, *args):
      
      if len(args) == 1:
          quantiles = args[0]
      else:
          quantiles = list(args)
  
      if not _is_non_string_iterable(quantiles):
          quantiles = [quantiles]
      query = ",".join([str(i) for i in quantiles])
      return ("__builtin__quantile__[" + query + "]", [src_column])
docs: Builtin approximate quantile aggregator for groupby.
      Accepts as an argument, one or more of a list of quantiles to query.
      For instance:
  
      To extract the median
  
      >>> sf.groupby("user",
      ...   {'rating_quantiles':tc.aggregate.QUANTILE('rating', 0.5)})
  
      To extract a few quantiles
  
      >>> sf.groupby("user",
      ...   {'rating_quantiles':tc.aggregate.QUANTILE('rating', [0.25,0.5,0.75])})
  
      Or equivalently
  
      >>> sf.groupby("user",
      ...     {'rating_quantiles':tc.aggregate.QUANTILE('rating', 0.25,0.5,0.75)})
  
      The returned quantiles are guaranteed to have 0.5% accuracy. That is to say,
      if the requested quantile is 0.50, the resultant quantile value may be
      between 0.495 and 0.505 of the true quantile.