text: from timeflux.core.node import Node
  import numpy as np
  import pandas as pd
  import json
  
  class Log(Node):
      """ Do a the log() of each element in the Dataframe
  
      Attributes:
          i (Port): Default input,expects Dataframe.
          o (Port): Default output,expects Dataframe.
  
      """
      def update(self):
          if not self.i.ready():
              return
          self.o = self.i
          self.o.data = np.log(self.o.data)
  