Bandpass filter in python... (I have no idea why scipy does not provide this)

bandpass.py

def bandpass(x, lowcut, highcut, fs, order=5, axis=-1, kind='butter'):
    """
    Parameters
    ----------
    x : ndarray
        1d time series data
    lowcut : float
        Defines lower frequency cutoff (e.g. in Hz)
    highcut : float
        Defines upper frequency cutoff (e.g. in Hz)
    fs : float
        Sampling frequency (e.g. in Hz)
    order : int
        Filter order parameter
    kind : str
        Specifies the kind of filter
    axis : int
        Axis along which to bandpass filter data
    """
    nyq = 0.5 * fs
    low = lowcut / nyq
    high = highcut / nyq
    if kind == "butter":
        b, a = butter(order, [low, high], btype="band")
    else:
        raise ValueError("Filter kind not recognized.")
    return filtfilt(b, a, x, axis=axis)