Minimalist Undo/Redo Editor

You are building a text editor that supports three operations: 'WRITE [word]', 'UNDO', and 'REDO'. 1. 'WRITE [word]' appends a word and a single space to the text. It also clears the entire 'redo' history. 2. 'UNDO' removes the last word added to the text and moves it to the redo history. 3. 'REDO' takes the last word from the redo history and appends it back to the text. Input: A single line of space-separated commands. 'WRITE' is always followed by one word. Output: The final string after all operations, with trailing spaces trimmed. Example: Input: WRITE Hello WRITE World UNDO WRITE Coding REDO Output: Hello Coding (Explanation: 'Hello' added, 'World' added, 'World' undone, 'Coding' added - this clears the redo stack, so 'REDO' does nothing.)