Check if argument defined via Argument object #148
Description
I'm trying to check if an argument is defined. I need to distinguish between the default value, which is valid to be passed manually, and the argument not being defined at all.
I'm aware of the Manager::defined() method, but that requires reparsing $argv and in my particular use case, $argv isn't even available in this section of code.
What I'd like is something like $climate->arguments->provided( $name ). Though that might be a bit confusing with exists and defined already available on that object. Having it only accessible on the Argument object would work too I think.
The method would check if Argument::$values is non-empty.
Happy to PR if you think this is workable.