code: def cov(self, x1, x2=None):
      if x2 is None:
          return self.amp2 * (
              self.cov_func(self.ls, x1, None)
              + 1e-6 * np.eye(x1.shape[0])
          )
      else:
          return self.amp2 * self.cov_func(self.ls, x1, x2)
  
file_path: auptimizer/src/aup/Proposer/spearmint/gp.py
imports: import numpy
  import scipy.linalg
  import scipy.optimize
  import scipy.io
label_desc: Use image node_id 3 for calling the GP obj's underlying member method code with example usage: obj.cov(x1, x2) and returns: unknown, unknown