The supplementary description is as follows: A pair of black swallows bumped into my window. I quickly opened the window, but the little guest suddenly disappeared. Outside the window is a piece of green spring. I wait at the window, waiting for the messenger of spring and happiness. My heart is also sprouting, like a young leaf facing the spring breeze, looking at the branches endlessly.
Swallows finally came back, flying around with mud and grass in their mouths, and built a small white house on the corner of my house. After a while, they went out and came back, squeaking, as if they had found a workshop and a job in this new place and were reporting their happiness to me.