code: function isAbstractType(type: GraphQLType): boolean {
    const rawType = getRawType(type);
    return (
      rawType instanceof GraphQLInterfaceType ||
      rawType instanceof GraphQLUnionType
    );
  }
docs: Determine if a type is abstract (not concrete).
  
  Note: This is used in place of the `graphql` version of the function in order
  to not break `instanceof` checks with Jest. This version also unwraps
  non-null/list wrapper types.