code: def value_at_risk(returns, cutoff=0.05):
      """
      Value at risk (VaR) of a returns stream.
  
      Parameters
      ----------
      returns : pandas.Series or 1-D numpy.array
          Non-cumulative daily returns.
      cutoff : float, optional
          Decimal representing the percentage cutoff for the bottom percentile of
          returns. Defaults to 0.05.
  
      Returns
      -------
      VaR : float
          The VaR value.
      """
      return np.percentile(returns, 100 * cutoff)
  
imports: from __future__ import division
  import math
  import pandas
  import numpy
  from math import pow
  from scipy import stats, optimize
  from six import iteritems
  from sys import float_info
  from .utils import nanmean, nanstd, nanmin, up, down, roll, rolling_window
  from .periods import ANNUALIZATION_FACTORS, APPROX_BDAYS_PER_YEAR
  from .periods import DAILY, WEEKLY, MONTHLY, QUARTERLY, YEARLY
label_desc: Use image node_id 53 for calling a global function with example usage: value_at_risk(returns, cutoff) and returns: np