Std.Mail.explain

fn

This is a callable function.

What it does

What a refusal says.

A refusal never repeats what it refused, for the same reason a validation

failure does not: the sender knows what they gave, and repeating it carries

whatever was in it somewhere else.

Read the signature

• The text after the name is the type checked by Pudu.
• Read arrows from left to right: inputs come first, and the final type is returned.
• & borrows a value for this call instead of moving or copying it.