code: def mahalanobis(x, y, vinv=_mock_identity):
      result = 0.0
  
      diff = np.empty(x.shape[0], dtype=np.float32)
  
      for i in range(x.shape[0]):
          diff[i] = x[i] - y[i]
  
      for i in range(x.shape[0]):
          tmp = 0.0
          for j in range(x.shape[0]):
              tmp += vinv[i, j] * diff[j]
          result += tmp * diff[i]
  
      return np.sqrt(result)
  
imports: import numpy
  import numba
  from pynndescent.optimal_transport import allocate_graph_structures, initialize_graph_structures, initialize_supply, initialize_cost, network_simplex_core, total_cost, ProblemStatus, sinkhorn_transport_plan
label_desc: Use image node_id 8 for calling a global function with example usage: mahalanobis(x, y, vinv) and returns: np