   end
 
   defp valid_key_identifier?([h|t]) \
-      when h >= ?a andalso h <= ?z   \
-      when h >= ?A andalso h <= ?Z   \
-      when h >= ?0 andalso h <= ?9 do
+      when h >= ?a and h <= ?z   \
+      when h >= ?A and h <= ?Z   \
+      when h >= ?0 and h <= ?9 do
     valid_key_identifier?(t)
   end
 

    false
  end

  defp only_spaces?([h|t]) when h == ?\s orelse h == ?\t, do: only_spaces?(t)
  defp only_spaces?(other), do: other == []

  # Tokenize the buffered text by appending

  # Start tokens finish with `do` or `->`
  # while end tokens contain only the end word.

  defp tip_expr_token_name([h|t]) when h == ?\s or h == ?\t do
    tip_expr_token_name(t)
  end

  defp tip_expr_token_name('od' ++ [h|_]) when h == ?\s or h == ?\t or h == ?) do
    :start_expr
  end

  defp tip_expr_token_name('>-' ++ [h|_]) when h == ?\s or h == ?\t or h == ?) do
    :start_expr
  end

