expands the filename if there is a . as leading path

def _expand_filename(self, line):
        """expands the filename if there is a . as leading path"""
        # expand .
        newline = line
        path = os.getcwd()
        if newline.startswith("."):
            newline = newline.replace(".", path, 1)
        # expand ~
        newline = os.path.expanduser(newline)
        return newline