code: def linear_dataset(a=2, size=1000):
      x = np.random.rand(size)
      y = x / 2
  
      x = x.reshape((-1, 1))
      y = y.reshape((-1, 1))
  
      return x, y
  
imports: import os
  from unittest import TestCase
  import numpy
  import pytest
  import tensorflow
  from bigdl.orca.learn.tf2 import Estimator
  from bigdl.orca.ray import OrcaRayContext
  from bigdl.orca import OrcaContext
label_desc: Use image node_id 1 for calling a global function with example usage: linear_dataset(a, size) and returns: x,  y