current-prefix-argcurrent-prefix-arg is a variable defined in `
C source code'. Its value is
nilDocumentation: The value of the prefix argument for this editing command. It may be a number, or the symbol `-' for just a minus sign as arg, or a list whose car is a number for just one or more C-u's or nil if no argument has been specified. This is what `(interactive "P")' returns.