def lowpass(self, frequency, q=0.707):
        """lowpass takes 2 parameters: filter frequency in Hz above which
        frequencies will be attenuated and q (default=0.707).

        Beware of clipping when using high q values.
        """
        self.command.append('lowpass')
        self.command.append(frequency)
        self.command.append(str(q) + 'q')
        return self
lowpass takes 2 parameters: filter frequency in Hz above which
        frequencies will be attenuated and q (default=0.707).

        Beware of clipping when using high q values.