def []=(key, value)
      characteristics[key] = Curation.new value, subject.class.characterization[key]
    end
def []=(key, value)
      characteristics[key] = Curation.new value, subject.class.characterization[key]
    end
Store a late-defined characteristic, with a Charisma wrapper.
 @param [Symbol] key The name of the characteristic, which must match one defined in the class's characterization
 @param value The value of the characteristic