Base R has had the function isTRUE() for many years, and I had wished for a few years that there were an isFALSE(), too. I had used identical(x, FALSE) many times before I added it to the first version of the xfun package as the function isFALSE(). The xfun package was first released to CRAN on 2018-01-22.

Three months later (2018-04-23), R 3.5.0 was released, which included a function named isFALSE() in the base package. Apparently another mind was thinking like me (which turned out to be …