subleq.py

prog = [ 21,  -1,  -2,  #0 
         19,  20,  -1,  #3 
         18,   0,  -2,  #6     
         17,  17,   0,  #9 
          0,   0,   0,  #12
          0,   0,   0,  #15
         -1,   1,  13,  #18
         72, 101, 108,  #21
        108, 111,  32,  #24
         87, 111, 114,  #27
        108, 100,  33,  #30
         10]            #33

pc=0  #Program counter.  The pointer to where we are

out="" #Somewhere to collect the output to display at the end
while True:
    #Load the next 3 values into a, b, c
    a,b,c=prog[pc:pc+3]

    #now what?

print out