isTRUE(x)
| x | Any value. | 
| isTRUE(x) | returns TRUE if x is a logical vector of length one whose value is TRUE. Otherwise it returns FALSE. | 
| isFALSE(x) | returns TRUE if x is a logical vector of length one whose value is FALSE. Otherwise it returns FALSE. | 
isTRUE(all.equal(sqrt(14), sqrt(2)*sqrt(7))) &&
    isTRUE(all.equal(1:2,1:3)) # FALSE
isTRUE( 2 == NaN ) # FALSE
# FALSE if this option not set or FALSE
isTRUE(getOption("unusualOption")) 
options(unusualOption = TRUE)
isTRUE(getOption("unusualOption")) # TRUE
options(unusualOption = FALSE)
isFALSE(getOption("unusualOption")) # TRUE
isTRUE(c(Value=TRUE))