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Currently, many of our modules have no .install file, yet they set Druapl Drupal system variables that would get left behind in the database if the module were disabled/removed. Adding this function to an existing .install file, or creating a blank .install file with just this function will remedy this. If the .install file already has a hook_uninstall() function, check the code to make sure it does something similar to this funciton to clean up its variables.
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