docstr: Choose a variable at random from the set of splittable variables
  Returns
  -------
      str - a variable name that can be split on
docstr_tok: ["Choose","a","variable","at","random","from","the","set","of","splittable","variables","Returns","--","--","--","-","str","-","a","variable","name","that","can","be","split","on"]
code: def random_splittable_variable(self) -> str:
      """
      Choose a variable at random from the set of splittable variables
      Returns
      -------
          str - a variable name that can be split on
      """
      if self.is_at_least_one_splittable_variable():
          return np.random.choice(
              np.array(self.splittable_variables()), 1
          )[0]
      else:
          raise NoSplittableVariableException()
  
imports: from operator import gt, le
  from typing import Any, List, Optional, Union
  import numpy
  import pandas
  from .errors import NoSplittableVariableException
  from .splitcondition import SplitCondition
label_desc: Use image node_id 8 for calling the CovariateMatrix obj's underlying member method code with example usage: obj.random_splittable_variable() and returns: np