Colon Sentences

Colons are for introducing lists and instructions (like this sentence):

• Please buy three things for me at the grocery store: cake, chocolates, and chips.
• This is how you make toast: put the slice of bread in the toaster, pull the lever down, and wait until your bread pops up.
• A problem came up when you were gone: the X501 broke down again and the technician suggested the machine is old and needs to be replaced.