def insert_cassette(name, options = {})
if turned_on?
if cassettes.any? { |c| c.name == name }
raise ArgumentError.new("There is already a cassette with the same name (#{name}). You cannot nest multiple cassettes with the same name.")
end
cassette = Cassette.new(name, options)
cassettes.push(cassette)
cassette
elsif !ignore_cassettes?
message = "VCR is turned off. You must turn it on before you can insert a cassette. " +
"Or you can use the `:ignore_cassette => true` option to completely ignore cassette insertions."
raise TurnedOffError.new(message)
end
end