code: def color_worker(srcs, window, ij, args):
      
      src = srcs[0]
      arr = src.read(window=window)
      arr = to_math_type(arr)
  
      for func in parse_operations(args["ops_string"]):
          arr = func(arr)
  
      # scaled 0 to 1, now scale to outtype
      return scale_dtype(arr, args["out_dtype"])
docs: A user function.