code: def ARDSE(ls, x1, x2=None, grad=False):
      cov = np.exp(-0.5 * dist2(ls, x1, x2))
      if grad:
          return (cov, grad_ARDSE(ls, x1, x2))
      else:
          return cov
  
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 4 for calling a global function with example usage: ARDSE(ls, x1, x2, grad) and returns: cov,  grad_ARDSE, cov