GraphQLUnionType documentation is incorrect

[berekuk]

GraphQLUnionType currently gives the following example of its usage:

class PetType(GraphQLUnionType):
    name = 'Pet'
    types = [DogType, CatType]

    def resolve_type(self, value, _type):
        if isinstance(value, Dog):
            return DogType()
        if isinstance(value, Cat):
            return CatType()

I believe this documentation is incorrect; PetType() can't be instantiated since GraphQLUnionType's __init__ takes name and types as required parameters.

Calling PetType(name=PetType.name, ...) is obviously terrible, and implementing an empty __init__ which doesn't call super() feels unsafe.

Also, even if there's a way to define a UnionType via inheritance which I'm missing, I don't see why GraphQLUnionType example should be different from GraphQLInterfaceType example, which uses the normal function call API.

[Cito]

You're right, the docstring is obviously incorrect - thanks for reporting. I commited a fix with hopefully proper example code now.