code: def min(self):
      if self.length == 0:
          return np.inf
      else:
          return self.root[2]
  
imports: import collections
  import numpy
  from chainerrl.misc.random import sample_n_k
label_desc: Use image node_id 2 for calling the MinTreeQueue obj's underlying member method code with example usage: obj.min() and returns: np, self