text: import visdom
  import time
  import numpy as np
  
  class Visualizer(object):
      def __init__(self, env='default', **kwargs):
          self.vis = visdom.Visdom(env=env, **kwargs)
          self.index = {}
      def plot_many_stack(self, d):
          '''
          self.plot('loss',1.00)
          '''
          name=list(d.keys())
          name_total=" ".join(name)
          x = self.index.get(name_total, 0)
          val=list(d.values())
          if len(val)==1:
              y=np.array(val)
          else:
              y=np.array(val).reshape(-1,len(val))
          #print(x)
          self.vis.line(Y=y,X=np.ones(y.shape)*x,
                      win=str(name_total),#unicode
                      opts=dict(legend=name,
                          title=name_total),
                      update=None if x == 0 else 'append'
                      )
          self.index[name_total] = x + 1