'Prints instructions for mapping control changes.'

def _print_instructions(self):

    print 'Enter    the    index    of    a    signal    to    set    the    control    change    for,    or    `q`    when    done.'
    fmt = '{:>6} DCTB {:<20} DCTB {:>6}'
    print fmt.format('Index', 'Control', 'Current')
    for (i, signal) in enumerate(self._signals):
        print fmt.format((i + 1), signal, self._cc_map.get(signal))
    print
