main:
    leal    4(%esp), %ecx       /* execution begins */
    andl    $-16, %esp
    pushl   -4(%ecx)
    pushl   %ebp
    movl    %esp, %ebp
    pushl   %ecx
    subl    $4, %esp
    call    walk                /* call walk with no arguments */
    movl    $0, %eax            /* exit code := 0 */
    addl    $4, %esp
    popl    %ecx
    popl    %ebp
    leal    -4(%ecx), %esp
    ret                         /* execution ends */