Is the " || "required when signcrypting?

[superpoincare]

According to the libsodium documentation,

`Finally, if, for some reason, you want to implement your own signcryption scheme:
If public verifiability is not required, sign (encryption_key || message) first then encrypt (recipient_id || signature || message).

…
`

I am curious if the vertical line characters and spaces are required, or is it written like that for ease of reading, because the sign function doesn't add the " || " itself.

[enkore]

|| means concatenation (often with implied length encoding if variable length)

[superpoincare]

Thank you.