input: Write a function to rewrite the given Python code using list comprehensions. If the code is already in list comprehension form, return the original code. If the code is empty, return an empty string.
  assert rewrite_with_comprehension("", "")==True
  assert rewrite_with_comprehension("even_numbers = [i for i in range(1, 21) if i % 2 == 0]", "even_numbers = [i for i in range(1, 21) if i % 2 == 0]")==True
  assert rewrite_with_comprehension("even_numbers = []\nfor i in range(1,21):\n    if i % 2 == 0:\n        even_numbers.append(i)", "even_numbers = [i for i in range(1, 21) if i % 2 == 0]")==True
  assert rewrite_with_comprehension("", "")==True
output: def rewrite_with_comprehension(original_code, expected_code):
      if not original_code:
          return True
      if original_code == expected_code:
          return True
      try:
          exec(original_code)
          exec(expected_code)
          return eval(original_code.split('=')[0].strip()) == eval(expected_code.split('=')[0].strip())
      except:
          return False