Pascal family (Object Pascal, Modula, Oberon, Ada, etc.) as well as PL/I, modern forms of Fortran and BASIC dialects influenced by Pascal, most functional languages, and many others. To allow multiple values to execute the same code (and avoid needing to duplicate code), Pascal-type languages permit any number of values per case, given as a comma-separated list, as a range, or as a combination. Languages derived from C language, and more generally those influenced by Fortran's computed GOTO, instead feature fallthrough, where control moves to the matching case, and then execution continues ("falls through") to the statements associated with the next case in the source text. This also allows multiple values to match the same point without any special syntax: they are just listed with empty bodies. Values can be special conditioned with code in the case body. In practice, fallthrough is usually prevented with a break keyword at the end of the matching body, which exits execution of the switch block, but this can cause bugs due to unintentional fallthrough if the programmer forgets to insert the break statement. This is thus seen by many as a language wart, and warned against in some lint tools. Syntactically, the cases are interpreted as labels, not blocks, and the switch and break statements explicitly change control flow. Some languages influenced by C, such as JavaScript, retain default fallthrough, while others remove fallthrough, or only allow it in special circumstances. Notable variations on this in the C-family include C#, in which all blocks must be terminated with a break or return unless the block is empty (i.e. fallthrough is used as a way to specify multiple values). In some cases languages provide optional fallthrough. For example, Perl does not fall through by default, but a case may explicitly do so using a continue keyword. This prevents unintentional fallthrough but allows it when desired. Similarly, Bash defaults to not falling through when terminated with ;;, but allow fallthrough with ;& or ;;& instead. An example of a switch statement that relies on fallthrough is Duff's device. Compilation Optimizing compilers such as GCC or Clang may compile a switch statement into either a branch table or a binary search through the values in the cases. A branch table allows the switch statement to determine with a small, constant number of instructions which branch to execute without having to go through a list of comparisons,