What that colon is saying is, I'm about to begin a sequence of instructions that I want to treat as a block.

这个冒号的意思是，下面的一系列的指令,要当做一整块来对待。

麻省理工公开课 - 计算机科学及编程导论课程节选

So on the left hand side of this particular languages environment I have some puzzle pieces and they are shaped and colored ; in a manner that hints out their functionality; any blocks that tell the Cat as we'll see in a moment, what to do something happen to be orange.

在这个程序语言界面的左手边有一些拼图,他们的形状和颜色代表他们的功能,我们马上就能看到;,任何一个给计算机发出指令的图块，都是橙色的。

哈佛公开课 - 计算机科学课程节选