Let's say I'm documenting a library function that (for example) accepts a number and returns the number squared. Should I write
This function squares the given number.
or
This function squares a given number?
At the time of writing the sentence, there is no particular number we'd be referring to. But at the time the function is executed, there is a concrete number that is being squared.
i = i + 1 //add one to i
)