Function wrap 

pub fn wrap(f: function) -> function

Creates a new coroutine with body f and returns a function that resumes it each time it is called. Arguments to that function pass into the coroutine, and its yielded values come back as results — but unlike resume, errors are propagated to the caller.

Examples

local gen = coroutine.wrap(function()
  for i = 1, 3 do coroutine.yield(i) end
end)
print(gen(), gen(), gen())    --> 1   2   3