class_docstr: Base class for multivariate kernels.
  
  An instance of MultivariateKernel implements a `call` method having
  signature `call(x, loc)`, returning the kernel weights comparing `x`
  (a 1d ndarray) to each row of `loc` (a 2d ndarray).
code: def _setup(self):
      # Precompute the squared bandwidth values.
      self.bwk = np.prod(self.bw)
      self.bw2 = self.bw * self.bw
  
imports: import numpy
  import scipy.sparse
  from scipy.sparse.linalg import svds
  from scipy.optimize import fminbound
  import warnings
  from statsmodels.tools.tools import Bunch
  from statsmodels.tools.sm_exceptions import IterationLimitWarning, iteration_limit_doc
label_desc: Use image node_id 3 for calling the MultivariateKernel obj's underlying member method code with example usage: obj._setup() without return types