pub fn main(world: World) -> Void raises {
    var reversed_buf: [6]u8 = [0_u8; 6]
    let reversed: Maybe<Span<u8>> = std.str.reverse(reversed_buf, "drawer")
    let trimmed: Span<u8> = std.str.trimAscii("  zero text  ")
    let left_trimmed: Span<u8> = std.str.trimStartAscii("  left")
    let right_trimmed: Span<u8> = std.str.trimEndAscii("right  ")
    var small: [3]u8 = [0_u8; 3]
    let overflow: Maybe<Span<u8>> = std.str.reverse(small, "drawer")
    var copy_buf: [4]u8 = [0_u8; 4]
    var concat_buf: [8]u8 = [0_u8; 8]
    var repeat_buf: [6]u8 = [0_u8; 6]
    var lower_buf: [4]u8 = [0_u8; 4]
    var upper_buf: [4]u8 = [0_u8; 4]
    let copied: Maybe<Span<u8>> = std.str.copy(copy_buf, "zero")
    let joined: Maybe<Span<u8>> = std.str.concat(concat_buf, "zero", "lang")
    let repeated: Maybe<Span<u8>> = std.str.repeat(repeat_buf, "ha", 3)
    let lowered: Maybe<Span<u8>> = std.str.toLowerAscii(lower_buf, "ZERO")
    let uppered: Maybe<Span<u8>> = std.str.toUpperAscii(upper_buf, "zero")
    var ok: Bool = true
    if !reversed.has {
        ok = false
    }
    if reversed.has {
        if !std.mem.eql(reversed.value, "reward") {
            ok = false
        }
    }
    if overflow.has {
        ok = false
    }
    if std.str.countByte("banana", 97_u8) != 3 {
        ok = false
    }
    if !std.str.startsWith("zero text syntax", "zero") {
        ok = false
    }
    if !std.str.endsWith("zero text syntax", "syntax") {
        ok = false
    }
    if !std.str.contains("zero text syntax", "text") {
        ok = false
    }
    if std.str.contains("zero text syntax", "column") {
        ok = false
    }
    if !std.str.contains("zero", "") {
        ok = false
    }
    if !std.mem.eql(trimmed, "zero text") {
        ok = false
    }
    if !std.mem.eql(left_trimmed, "left") || !std.mem.eql(right_trimmed, "right") {
        ok = false
    }
    if !copied.has || !joined.has || !repeated.has || !lowered.has || !uppered.has {
        ok = false
    }
    if copied.has && !std.mem.eql(copied.value, "zero") {
        ok = false
    }
    if joined.has && !std.mem.eql(joined.value, "zerolang") {
        ok = false
    }
    if repeated.has && !std.mem.eql(repeated.value, "hahaha") {
        ok = false
    }
    if lowered.has && !std.mem.eql(lowered.value, "zero") {
        ok = false
    }
    if uppered.has && !std.mem.eql(uppered.value, "ZERO") {
        ok = false
    }
    if std.str.count("aaaa", "aa") != 2 {
        ok = false
    }
    if std.str.indexOf("zero text syntax", "text") != 5 || std.str.lastIndexOf("one two one", "one") != 8 {
        ok = false
    }
    if !std.str.eqlIgnoreAsciiCase("Zero", "zero") {
        ok = false
    }
    if std.str.wordCountAscii("zero text syntax") != 3 {
        ok = false
    }
    if ok {
        check world.out.write("std str ok\n")
    }
}