<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def runtime_paths(self):
 # TODO: memoize """All the runtime paths of ensime-vim plugin files."""

        runtimepath = self._vim.options['runtimepath']
        plugin = "ensime-vim"
        paths = []

        for path in runtimepath.split(','):
            if plugin in path:
                paths.append(os.path.expanduser(path))

        return paths