In R, every comma matters. When creating a vector, c(1, 2, 5) will do the right thing, but add one unfortunate comma and c(1, 2, 5,) will greet you with a deadly Error in c(1, 2, 5, ) : argument 4 is empty.
Other languages like Perl are less strict when defining basic data structures: having a comma after...





Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).