code: def MakePmfFromItems(t, name=''):
      
      pmf = Pmf(dict(t), name)
      pmf.Normalize()
      return pmf
docs: Makes a PMF from a sequence of value-probability pairs
  
      Args:
          t: sequence of value-probability pairs
          name: string name for this PMF
  
      Returns:
          Pmf object