is_other_script s returns true when the file with name s starts with a magic string that indicates a script other than posix shell, otherwise it returns false. Raises Sys_error when the file cannot be opened.

is_elf s returns true when the file with name s starts with the magic number for ELF, otherwise it returns false. Raises Sys_error when the file cannot be opened.

parse_file s attempts to parse the file with name s, and returns its concrete syntax tree.

parse_string s c attempts to parse the file with name s whose contents is c, and returns its concrete syntax tree.