--- Returns numerical code, nil if index out of range, default i=1.
function byte(s [, i])
--- Returns a string built from 0 or more integers.
function char(i1, i2, ...)
--- Returns binary representation of function, used with loadstring.
function dump(function)
--- Matches pattern in s, returns start,end indices, else nil.
function find(s, pattern [, init [, plain]])
--- Returns formatted string, printf-style.
function format(formatstring, e1, e2, ...)
--- Returns iterator function that returns next captures from pattern pat on s.
function gfind(s, pat)
--- Returns copy of s with pat replaced by repl, and substitutions made.
function gsub(s, pat, repl [, n])
--- Returns string length.
function len(s)
--- Returns string with letters in lower case.
function lower(s)
--- Returns string with n copies of string s.
function rep(s, n)
--- Returns substring from index i to j of s, default j=-1(string length).
function sub(s, i [, j])
--- Returns string with letters in upper case.
function upper(s)

---
-- Converts a string from one character set to another using iconv().
-- Valid character sets are ones GLib's g_convert() accepts, typically GNU
-- iconv's character sets.
-- @param text The text to convert.
-- @param to The character set to convert to.
-- @param from The character set to convert from.
function iconv(text, to, from) end