Argument need not be optional to have a default value defined

[gpj1]

Closes #

Description

Current documentation about Arguments says that "When an argument is optional, we can define a default value ..."
This seems to be misleading because a default value for an argument can be defined irrespective of optional or mandatory argument.

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[benjie]

Interesting nuance; technically you can’t define a default value for a non-optional argument, since an optional argument is one that is either nullable or has a default value, but this is a bit if a circular argument! Thanks for bringing this to our attention, definitely feels like the wording could be cleaned up 👍