code: def proportion_of_value_in_variable(
      self, variable: int, value: float
  ) -> float:
      if self.is_column_unique(variable):
          return 1.0 / self.n_obsv
      else:
          return float(np.mean(self.get_column(variable) == value))
  
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 12 for calling the CovariateMatrix obj's underlying member method code with example usage: obj.proportion_of_value_in_variable(variable, value) and returns: unknown, float