In Vim, the p key is used for putting (otherwise known as pasting) text from a register. The p key leaves the cursor at the beginning of the newly-putted text — gp, however, puts the cursor just after the newly-putted text.
At glance, this doesn’t seem very useful. But it is a good keymap to know!
Because gp places the cursor at the end of the newly-putted text, it behaves differently when it is repeated with the . command. This is useful for when you want to insert a particular block of text between a set of lines.
Give this a go in the editor. Yank the return false line under the first case statement in the switch with yy. Then, put it under the second case statement using gp. Then, repeat the same action for the other case statements using the . keymap in normal mode.