class Steep::TypeInference::LocalVariableTypeEnv

def annotate(collection)
  decls = collection.var_type_annotations.each.with_object({}) do |(var, annotation), hash|
    type = collection.var_type(lvar: var)
    hash[var] = Entry.new(type: type, annotations: [annotation])
  end
  decls.each do |var, annot|
    inner_type = annot.type
    outer_type = self[var]
    if outer_type
      relation = Subtyping::Relation.new(sub_type: inner_type, super_type: outer_type)
      constraints = Subtyping::Constraints.new(unknowns: Set.new)
      subtyping.check(relation, constraints: constraints, self_type: self_type).else do |result|
        yield var, outer_type, inner_type, result
      end
    end
  end
  new_decls = declared_types.merge(decls)
  new_assigns = assigned_types.reject {|var, _| new_decls.key?(var) }
  update(declared_types: new_decls, assigned_types: new_assigns)
end