Say I have a dictionary like the following
{1:'one',2:'two',4:'three',8:'four',16:'five', etc...}
and I am given some numbers, say 22, 25, and 9. I want to determine the
keys, powers of 2, that comprise the number.
Ex. 22 = 16+4+2
25 = 16+8+1
9 = 8+1
...etc...
How do I get these keys?