如何在两行之间留出空格？

line1 = "This is line 1."
line2 = "This is line 2."
space = " "  # 空格字符

output = line1 + "\n" + space + "\n" + line2
print(output)

This is line 1.

 This is line 2.

<p>This is line 1.</p>
<p class="spacer"></p>
<p>This is line 2.</p>

<style>
.spacer {
  margin-top: 10px;  /* 上间距 */
  margin-bottom: 10px;  /* 下间距 */
}
</style>