code: def variance(samples, weights=None):  # ,tol=0, _mean=None):
      """calculate the (weighted) variance for a list of points
  
      Args:
          samples (list): a list of sample points
          weights (list, default=None): a list of sample weights
  
      Returns:
          the weighted variance for a list of sample points"""
      return moment(samples, weights, order=2)
  
imports: from mystic.math.stats import *
  from mystic.math.samples import *
  from mystic.math.integrate import *
  from mystic.symbolic import generate_solvers, generate_constraint, solve
  from mystic.symbolic import generate_conditions, generate_penalty
  from mystic.math import almostEqual
  from mystic.math.distance import Lnorm
  from numpy import asarray
label_desc: Use image node_id 19 for calling a global function with example usage: variance(samples, weights) and returns: moment