def num_channels(self):
return <NUM_LIT:1><EOL>
Query the number of channels implemented by the
PatternGenerator. In case of single-channel generators this
will return 1; in case of multichannel, it will return the
number of channels (eg, in the case of RGB images it would
return '3', Red-Green-Blue, even though the OrderedDict
returned by channels() will have 4 elements -- the 3 channels
+ their average).