A trap for young players with the lapply() function.

I think that the suggestion I made, in response to a posting by
Barry Rowlingson, that the first argument of lapply() be given the name of
".X" rather than just-plain-X, would be (a) effective, and (b) harmless.

It would break any call to *apply() that used X= to name the first
argument. There are currently 3020 such calls in the R code in CRAN.

One can avoid the problem by creating the function given as the FUN
argument when one calls lapply() and the like.  Don't give that
function arguments named "X", "FUN", "USE.NAMES", etc. and perhaps
make use of R's lexical scoping to avoid having to use many arguments
to the function.  E.g., instead of
    sapply(1:5, sin)
use
    sapply(1:5, function(theta) sin(theta))
or instead of
    myY <- 3
    sapply(1:5, atan2, y=myY)
use
    myY <- 3
    sapply(1:5, function(x) atan2(myY, x))