# requires Ruby 3.3 or newer

body = proc { |x| x * 2 }

# *** before: ***
wrapped_old = lambda(&body) # a Proc was silently accepted, arity was not
#checked

# *** in version 3.3: ***
begin
  lambda(&body)   # ArgumentError: tried to create a Proc from a non-literal Proc
rescue ArgumentError => e
  puts e.message
end

strict = lambda { |x| x * 2 }   # only a literal block is accepted
puts strict.call(3)