using gee

I have this trial function to use gee,

trygee <- function (x, id) {
  y <- x + rnorm(length(x))
  dat <- data.frame(x=x, y=y, id=id)
  foo <- gee(y ~ x, id, data=dat)
  foo$coeffcients
}

trygee(rnorm(100), id = 1:100)

Error in model.frame.default(formula = y ~ x, id = id, data = dat) : 
	Object "dat" not found

Since I want to use gee within a function to be called again and again,
what's the proper way to do this?  Thanks.

Jun

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