code: def normalize(x):
      '''normalize x to have mean 0 and unity standard deviation'''
      x = x.astype(float)
      x -= x.mean()
      return x / float(x.std()f normalize(x):
      '''normalize x to have mean 0 and unity standard deviation'''
      x = x.astype(float)
      x -= x.mean()
      return x / float(x.std())
docs: normalize x to have mean 0 and unity standard deviation