code: def coskewness(X, Y, Z, condition=None, **kwargs):
      r"""
      Calculates the co-skewness of three random variables.
  
      Explanation
      ===========
  
      Mathematically Coskewness is defined as
  
      .. math::
          coskewness(X,Y,Z)=\frac{E[(X-E[X]) * (Y-E[Y]) * (Z-E[Z])]} {\sigma_{X}\sigma_{Y}\sigma_{Z}}
  
      Parameters
      ==========
  
      X : RandomSymbol
              Random Variable used to calculate coskewness
      Y : RandomSymbol
              Random Variable used to calculate coskewness
      Z : RandomSymbol
              Random Variable used to calculate coskewness
      condition : Expr containing RandomSymbols
              A conditional expression
  
      Examples
      ========
  
      >>> from sympy.stats import coskewness, Exponential, skewness
      >>> from sympy import symbols
      >>> p = symbols('p', positive=True)
      >>> X = Exponential('X', p)
      >>> Y = Exponential('Y', 2*p)
      >>> coskewness(X, Y, Y)
      0
      >>> coskewness(X, Y + X, Y + 2*X)
      16*sqrt(85)/85
      >>> coskewness(X + 2*Y, Y + X, Y + 2*X, X > 3)
      9*sqrt(170)/85
      >>> coskewness(Y, Y, Y) == skewness(Y)
      True
      >>> coskewness(X, Y + p*X, Y + 2*p*X)
      4/(sqrt(1 + 1/(4*p**2))*sqrt(4 + 1/(4*p**2)))
  
      Returns
      =======
  
      coskewness : The coskewness of the three random variables
  
      References
      ==========
  
      .. [1] https://en.wikipedia.org/wiki/Coskewness
  
      """
      num = expectation(
          (X - expectation(X, condition, **kwargs))
          * (Y - expectation(Y, condition, **kwargs))
          * (Z - expectation(Z, condition, **kwargs)),
          condition,
          **kwargs,
      )
      den = (
          std(X, condition, **kwargs)
          * std(Y, condition, **kwargs)
          * std(Z, condition, **kwargs)
      )
      return num / den
  
imports: from sympy.sets import FiniteSet
  from sympy.core.numbers import Rational
  from sympy.core.relational import Eq
  from sympy.core.symbol import Dummy
  from sympy.functions.combinatorial.factorials import FallingFactorial
  from sympy.functions.elementary.exponential import exp, log
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.elementary.piecewise import piecewise_fold
  from sympy.integrals.integrals import Integral
  from sympy.solvers.solveset import solveset
  from .rv import probability, expectation, density, where, given, pspace, cdf, PSpace, characteristic_function, sample, sample_iter, random_symbols, independent, dependent, sampling_density, moment_generating_function, quantile, is_random, sample_stochastic_process
label_desc: Use image node_id 13 for calling a global function with example usage: coskewness(X, Y, Z, condition) and returns: unknown