class_docstr: bilogistic model of Coles and Tawn 1994, Joe, Smith and Weissman 1992
  
  restrictions:
   - (beta, delta) in (0,1)^2 or
   - (beta, delta) in (-inf,0)^2
  
  not vectorized because of numerical integration
code: def _check_args(self, beta, delta):
      cond1 = (
          (beta > 0) and (beta <= 1) and (delta > 0) and (delta <= 1)
      )
      cond2 = (beta < 0) and (delta < 0)
      return cond1 | cond2
  
imports: import numpy
  from scipy import stats
  from statsmodels.tools.numdiff import _approx_fprime_cs_scalar, approx_hess
label_desc: Use image node_id 1 for calling the AsymBiLogistic obj's underlying member method code with example usage: obj._check_args(beta, delta) and returns: unknown