dictof all the traits of this class. The dictionary is keyed on the name and the values are the TraitType objects.
The TraitTypes returned don’t know anything about the values that the various HasTrait’s instances are holding.
The metadata kwargs allow functions to be passed in which filter traits based on metadata values. The functions should take a single value as an argument and return a boolean. If any function returns False, then the trait is not included in the output. If a metadata key doesn’t exist, None will be passed to the function.