input: Write a function to rewrite the given Python code using list comprehensions. If the input code is provided as a string, return the output code as a string. If the input code is empty, return an empty string.
  assert rewrite_code("""even_numbers = []
  for i in range(1,21):
      if i % 2 == 0:
          even_numbers.append(i)""") == """even_numbers = [i for i in range(1, 21) if i % 2 == 0]"""
  assert rewrite_code("") == ""
output: def rewrite_code(code):
      if not code:
          return ""
      lines = code.strip().split('\n')
      var_name = lines[0].split('=')[0].strip()
      start = int(lines[1].split('range(')[1].split(',')[0].strip())
      end = int(lines[1].split('range(')[1].split(',')[1].strip().rstrip('):'))
      condition = lines[2].split('if ')[1].strip()
      return f"{var_name} = [{lines[1].split('for ')[1].split(' in')[0].strip()} for {lines[1].split('for ')[1].split(' in')[0].strip()} in range({start}, {end + 1}) if {condition}]"