code: def __init__(self, mean, cov):
      self.mean = mu
      self.cov = cov
      self.sigmax, self.sigmaxy, tmp, self.sigmay = np.ravel(cov)
      self.nvars = 2
  
imports: import numpy
  from scipy import special
  from statsmodels.sandbox.distributions.multivariate import mvstdtprob
  from .extras import mvnormcdf
label_desc: Use image node_id 1 to create a new BivariateNormal object  with example: obj = BivariateNormal(mean, cov)