Calling survfit within a function

I have a function that generates data and tries to apply the survfit 
within it.  I have tried:

function(..){
x .....
survfit(Surv(tim,sts) ~ grp, data = x, envir = sys.frame(sys.parent()))
}

but I still get "Error: Object "x" not found".  Is there a fix?
(I use R-0.63.2 with the current survival4 package)

Thanks
E. S. Venkatraman
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