example1 <- mplusObject(MODEL = "mpg ON wt;",
  rdata = mtcars, autov = FALSE)
example1$usevariables
MplusAutomation:::detectVariables(example1)
example2 <- mplusObject(MODEL = "mpg ON wt;",
  rdata = mtcars, autov = TRUE)
example2$usevariables
example3 <- update(example2,
  MODEL = ~ . + "mpg ON qsec; wt WITH qsec;",
  autov = TRUE)
example3$usevariables
rm(example1, example2, example3)
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