code: def pdf(self, x):
      return bivariate_normal(x, self.mean, self.cov)
  
imports: import numpy
  from scipy import special
  from statsmodels.sandbox.distributions.multivariate import mvstdtprob
  from .extras import mvnormcdf
label_desc: Use image node_id 3 for calling the BivariateNormal obj's underlying member method code with example usage: obj.pdf(x) and returns: bivariate_normal