We're going to stray from the topic for a moment to talk about coding style.
Put the following code into your
echom "foo" . \ "bar" . \ "baz"
Restart Vim and run
:messages to see that Vim echoed "foobarbaz" to the
A backslash at the beginning of a line in a Vimscript file tells Vim that this line is a continuation of the previous one. This is unlike Python where the backslash goes at the end of the first line, instead of the beginning of the second.
This lets you split long lines for easier readability.