ANYSXP.Rd
ANYSXP is an object-like macro defining the SEXPTYPE type of "any" objects.
ANYSXP
SEXPTYPE
#define ANYSXP 18 /* make "any" args work.
In Rinternals.h.
https://cran.r-project.org/doc/manuals/r-patched/R-ints.html#SEXPTYPEs
SEXPTYPE, TYPEOF