def split_channels(data):
    """
    Splits a stereo signal into two mono signals (left and right respectively).

    Example:
    >>> data_left, data_right = split_channels(data)

    """
    if len(data[0]) == 2:
        data_l = data[:, 0]
        data_r = data[:, 1]
        return data_l, data_r
    else:
        print("Signal should be stereo.")
        return data