code: def _std_tuple_of(var=None, std=None, interval=None):
      """
      Convienence function for plotting. Given one of var, standard
      deviation, or interval, return the std. Any of the three can be an
      iterable list.
  
      Examples
      --------
      >>>_std_tuple_of(var=[1, 3, 9])
      (1, 2, 3)
  
      """
  
      if std is not None:
          if np.isscalar(std):
              std = (std,)
          return std
  
      if interval is not None:
          if np.isscalar(interval):
              interval = (interval,)
  
          return norm.interval(interval)[1]
  
      if var is None:
          raise ValueError("no inputs were provided")
  
      if np.isscalar(var):
          var = (var,)
      return np.sqrt(var)
  
imports: from __future__ import absolute_import, division, unicode_literals
  import math
  from math import cos, sin
  import random
  import warnings
  import numpy
  from numpy.linalg import inv
  import scipy.linalg
  import scipy.sparse
  import scipy.sparse.linalg
  from scipy.stats import norm, multivariate_normal
label_desc: Use image node_id 20 for calling a global function with example usage: _std_tuple_of(var, std, interval) and returns: np, std, norm