c.Value("tx") and c.Bind

[beatscode]

Hello, Just studying the code to gain some understanding. I was wondering the following

What does tx := c.Value("tx").(*pop.Connection) achieve here? Value method doesn't tell me more than just getting the key value from the current context. Just not clear where tx comes from.
https://github.com/gobuffalo/toodo/blob/master/actions/todos.go#L36

I'm also wondering what c.Bind() does as well.

Any clarification would be appreciated. Thanks