print(x) = print(stdout, x)

print(x1, x2) = print(stdout, x1, x2)

println(x) = print(stdout, x, "\n")

println(x1, x2) = print(stdout, x1, x2, "\n")

print(xs...) = print(stdout, xs...)

println(xs...) = print(stdout, xs..., "\n") # fewer allocations than `println(stdout, xs...)`

println(io::IO) = print(io, "\n")

function show end

function repr end

struct DevNull <: IO end

const devnull = DevNull()

write(::DevNull, ::UInt8) = 1

unsafe_write(::DevNull, ::Ptr{UInt8}, n::UInt)::Int = n

closewrite(::DevNull) = nothing

close(::DevNull) = nothing

wait_close(::DevNull) = wait()

bytesavailable(io::DevNull) = 0

let CoreIO = Union{Core.CoreSTDOUT, Core.CoreSTDERR}

global write(io::CoreIO, x::UInt8) = Core.write(io, x)

global unsafe_write(io::CoreIO, x::Ptr{UInt8}, nb::UInt) = Core.unsafe_write(io, x, nb)

CoreIO = Union{CoreIO, DevNull}

global read(::CoreIO, ::Type{UInt8}) = throw(EOFError())

global isopen(::CoreIO) = true

global isreadable(::CoreIO) = false

global iswritable(::CoreIO) = true

global flush(::CoreIO) = nothing

global eof(::CoreIO) = true

global wait_readnb(::CoreIO, nb::Int) = nothing

stdin::IO = devnull

stdout::IO = Core.stdout

stderr::IO = Core.stderr