code: def depth(self, channels):
      min_channel = min(channels, self.min_channel)
      return max(min_channel, int(channels * self.channel_ratio))
  
imports: import paddle.nn
  from paddleseg import utils
  from paddleseg.cvlibs import manager
label_desc: Use image node_id 2 for calling the PortraitNetHead obj's underlying member method code with example usage: obj.depth(channels) and returns: max