class_docstr: An abstract class for computing distances between neural networks. 
docstr: Evaluates the distance between the two networks x1 and x2. 
docstr_tok: ["Evaluates","the","distance","between","the","two","networks","x1","and","x2","."]
code: def evaluate_single(self, x1, x2, *args, **kwargs):
      """Evaluates the distance between the two networks x1 and x2."""
      raise NotImplementedError("Implement in a child class.")
  
imports: import numpy
  from .None import neural_network
  from ..gp.kernel import ExpSumOfDistsKernel, SumOfExpSumOfDistsKernel
  from ..utils.oper_utils import opt_transport
label_desc: Use image node_id 5 for calling the NNDistanceComputer obj's underlying member method code with example usage: obj.evaluate_single(x1, x2) without return types