Complete main()

#  main()
#  {
#    int a;                      // a: 0($fp)
#    a = mysub( 6 );
#    print( a );
#  }
         .text
         .globl  main
main:
         # prolog 
         # 1. when main gets control from QTSPIM
         # the stack pointer points to the top
         # of the stack.         
                               
         sub    $fp,$sp-4         #   2. $fp = $sp - space_for_variables
         
         move   $sp,$fp           #   3. $sp = $fp
                 
                                  # subroutine call
                                  #   7. No T registers to push
         li      $a0,6            #   8. Put argument into $a0
         jal     mysub            #   9. Jump and link to subroutine

                                  # regaining control from  the subroutine 
                                  #   Return value is in $v0
                                  #   10. No T registers to restore
                                  
         sw     $v0,0($fp)        # a = mysub( 6 )
        
                                  # print a               
         lw     $a0,0($fp)        # load a into $a0      
         li     $v0,1             # print integer service
         syscall
                                  # epilog                           
         li      $v0,10           # 11. return to QTSPIM
         syscall                  # 12.