input: Write a python function to interleave lines from two strings, aligning them line by line.
  assert align_strs("a\nb\nc", "1\n2\n3") == "a\n1\nb\n2\nc\n3\n"
  assert align_strs("line1\nline2", "A\nB\nC\nD") == "line1\nA\nline2\nB\nC\nD\n"
  assert align_strs("x\ny", "1") == "x\n1\ny\n"
output: def align_strs(str1, str2):
      lines1 = str1.split('\n')
      lines2 = str2.split('\n')
      max_len = max(len(lines1), len(lines2))
      result = []
      for i in range(max_len):
          if i < len(lines1):
              result.append(lines1[i])
          if i < len(lines2):
              result.append(lines2[i])
      return '\n'.join(result) + '\n'