<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def raise_from_response(resp):
 """Turn a failed request response into a BackendError. Handy for reflecting HTTP errors from farther back in the call chain. Parameters resp: :class:`requests.Response` Raises ------ :class:`apikit.BackendError` If `resp.status_code` is equal to or greater than 400. """

    if resp.status_code < 400:
        # Request was successful.  Or at least, not a failure.
        return
    raise BackendError(status_code=resp.status_code,
                       reason=resp.reason,
                       content=resp.text)