code: def sd_population(self):
      return np.sqrt(StandardScaler(with_mean=False).fit(self.v).var_)
  
imports: from typing import Optional, Callable, List
  import numpy
  import pandas
  from scattertext.termranking import AbsoluteFrequencyRanker
  from scipy.sparse import csc_matrix, csr_matrix
  from sklearn.preprocessing import StandardScaler
  from scattertext.smoothing.lowess import Lowess
  from scattertext.termranking.TermRanker import TermRanker
  from scattertext.TermDocMatrix import TermDocMatrix
label_desc: Use image node_id 4 for calling the Dispersion obj's underlying member method code with example usage: obj.sd_population() and returns: np