   end
 
   def delete_expressions line do
-    Enum.reduce(@delete_expressions, line, fn regex, repl -> Regex.replace(regex, repl, "") end)
+    Enum.reduce(@delete_expressions, line,
+                fn regex, repl -> Regex.replace(regex, repl, "\\1") end)
   end
 
   @doc """

defmodule Logfilt do

  @match_table [
          {~r/INFO/, :green},
          {~r/WARNING/, :yellow},
          {~r/ERROR/, :red},
          {~r/CRITICAL/, :magenta},
          {~r/^.*!!!.*$/, :cyan},
          {~r/\d{4}-\d{2}-\d{2}[^]]*]/, :grey},
      ]

  @delete_lines [
    ~r/recording\.py/,

  """
  def maybe_colorize_partial priority, color, pat, line do
    Regex.scan(pat, line, return: :index)
    |> Enum.map(fn [{start, len}|_] -> {priority, start, len, color} end)
  end

  @doc """
