main:
li $a0,7
jal timesNine
nop # set a breakpoint on this line before running

timesThree:
add $t0,$a0,$a0
add $v0,$t0,$a0
jr $ra

timesNine:
# at this point, $ra tells us where timesNine should return to
add $sp,$sp,-4
sw $ra,0($sp) # store into fresh memory allocated by the add
jal timesThree
move $a0,$v0
jal timesThree
# put the right return address for timesNine back into $ra
lw $ra,0($sp)
add $sp,$sp,4
jr $ra