import warnings


def filt(signal, synapse, dt, axis=0, x0=None, copy=True):
    """Filter ``signal`` with ``synapse``.

    .. note:: Deprecated in Nengo 2.1.0.
              Use `.Synapse.filt` method instead.
    """
    warnings.warn("Use ``synapse.filt`` instead", DeprecationWarning)
    return synapse.filt(signal, dt=dt, axis=axis, y0=x0, copy=copy)