In some programming languages, it is possible to group the digits in the program's source code to make it easier to read; see Integer literal: Digit separators. Ada, C# (from version 7.0), D, Haskell (from GHC version 8.6.1), Java, OCaml, Perl, Python (from version 3.6), PHP (from version 7.4[33]), Ruby, Go (from version 1.13), Rust, Julia, and Swift use the underscore (_) character for this purpose; as such, these languages allow seven hundred million to be entered as 700_000_000. Fixed-form Fortran ignores whitespace (in all contexts), so 700 000 000 is permissible.