code: def cityblock(u, v):
      """Compute the City Block (Manhattan) distance between two 1-D arrays.
  
      The City Block distance is defined as
  
      .. math::
          d(u, v) = \\sum_{i} |u_i - v_i|
  
      Args:
          u (array_like): Input array of size (N,)
          v (array_like): Input array of size (N,)
  
      Returns:
          cityblock (double): The City Block distance between
          vectors `u` and `v`.
      """
      if not pylibraft_available:
          raise RuntimeError("pylibraft is not installed")
      u = cupy.asarray(u)
      v = cupy.asarray(v)
      output_arr = cupy.zeros((1,), dtype=u.dtype)
      pairwise_distance(u, v, output_arr, "cityblock")
  
      return output_arr[0]
  
imports: import cupy
label_desc: Use image node_id 6 for calling a global function with example usage: cityblock(u, v) and returns: output_arr