color: move 'write-err' logic to the core ui class This is similar to what we needed for 'write', we move the logic from the extension to the core class. Beside the dispatch to 'win32print', we just apply label to the argument.

ui: extract low level part of 'write_err' in its own method Same as for 'write' and '_write' we needs it available for some of the color logic.

ui: extract buffer write from protect and timed 'write_err' output That subcall to 'self.write' is never doing actual write but only store things in buffers. So we do not need to protect it for exception not to time its execution. This will make it easier to extract a '_write_err' function as we did for 'write'.

color: move 'write' logic to the core ui class One more step, the support for writing color is not directly in core. No behavior change for the default case ('_colormode' = None). Here are the details of what we have to change to the core method: * apply to 'self.label' to input in the buffered case * dispatch to 'win32print' when applicable * apply to 'self.label' to input when applicable

ui: extract the low level part of 'write' in a dedicated function We are about to add some extra logic related to color. That logic will need to access the low level layer of ui doing the actual write to a stream. (eg: 'win32print'). We extract this logic into a private method for this purpose.

color: add multiple messages input support to 'win32print' All other function doing writes support any number of input message. For simplicity, we make 'win32print' able to do the same.

color: clarify name of an argument of 'win32print' In the current code, the function called to write happens to the 'orig' version of the method calling 'win32print' (obtained with a 'super' call). However, the variable could have a better name. That will be useful when we'll stop having inheritance in play.

color: move the 'colorlabel' call to the core 'ui' class This bring us closer to supporting color in core natively. Core already have a 'label' method that was a no-op. We update its to call the new 'colorlabel' function. Behavior is unchanged when colormode = None.

color: move the 'colorlabel' function in the core module The extract code is relocated in core.

color: extract the label code into its own function We extract the logic into a function. This will allow us to move the logic into the core 'color' module and later call it directly from core.