code: def ref_data(
      self, dtype, dshape, sizes, ratios, offsets, steps, clip
  ):
      in_height = dshape[2]
      in_width = dshape[3]
      num_sizes = len(sizes)
      num_ratios = len(ratios)
      size_ratio_concat = sizes + ratios
      steps_h = steps[0] if steps[0] > 0 else 1.0 / in_height
      steps_w = steps[1] if steps[1] > 0 else 1.0 / in_width
      offset_h = offsets[0]
      offset_w = offsets[1]
  
      out_shape = (
          1,
          in_height * in_width * (num_sizes + num_ratios - 1),
          4,
      )
  
      np_in = np.random.uniform(size=dshape).astype(dtype)
      np_out = np.zeros(out_shape).astype(dtype)
  
      for i in range(in_height):
          center_h = (i + offset_h) * steps_h
          for j in range(in_width):
              center_w = (j + offset_w) * steps_w
              for k in range(num_sizes + num_ratios - 1):
                  w = (
                      size_ratio_concat[k] * in_height / in_width / 2.0
                      if k < num_sizes
                      else size_ratio_concat[0]
                      * in_height
                      / in_width
                      * math.sqrt(size_ratio_concat[k + 1])
                      / 2.0
                  )
                  h = (
                      size_ratio_concat[k] / 2.0
                      if k < num_sizes
                      else size_ratio_concat[0]
                      / math.sqrt(size_ratio_concat[k + 1])
                      / 2.0
                  )
                  count = (
                      i * in_width * (num_sizes + num_ratios - 1)
                      + j * (num_sizes + num_ratios - 1)
                      + k
                  )
                  np_out[0][count][0] = center_w - w
                  np_out[0][count][1] = center_h - h
                  np_out[0][count][2] = center_w + w
                  np_out[0][count][3] = center_h + h
      if clip:
          np_out = np.clip(np_out, 0, 1)
  
      return np_in, np_out
  
imports: import math
  import sys
  import numpy
  import pytest
  import tvm
  import tvm.testing
  import tvm.topi.testing
  from tvm import te, topi
  from tvm.topi.vision import ssd, non_max_suppression, get_valid_counts
label_desc: Use image node_id 1 for calling the TestMultiboxPrior obj's underlying member method code with example usage: obj.ref_data(dtype, dshape, sizes, ratios, offsets, steps, clip) and returns: np_in,  np_out