<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def remove_if_exists(filename):
 """ Remove file. This is like :func:`os.remove` (or :func:`os.unlink`), except that no error is raised if the file does not exist. """

    try:
        os.unlink(filename)
    except OSError as ex:
        if ex.errno != errno.ENOENT:
            raise