class Steep::AST::Types::Nil

def ==(other)
  other.is_a?(Nil)
end

def back_type
  Name::Instance.new(name: Builtin::NilClass.module_name,
                     args: [],
                     location: location)
end

def free_variables
  Set.new
end

def hash
  self.class.hash
end

def initialize(location: nil)
  @location = location
end

def level
  [0]
end

def subst(s)
  self
end

def to_s
  "nil"
end

def with_location(new_location)
  self.class.new(location: new_location)
end