Equality

How to test things?

PeopleTree tree
    content = joe
    children = [jack]

PeopleTree clone
    content = joe
    children = [jack]


tree == clone         # true
tree == PeopleTree    # error: PeopleTree is not a value (this is subject to change/discussion)


tree is    Animal       # false
tree is Tree         # error: incomplete type
tree is PeopleTree   # true
tree is Tree(Person) # true
tree is Tree(?)      # true