Once upon a time, there were four little pigs who lived in a four-byte
ASCII file.  The first little piggy was an H.  The second little piggy
was a T.  The third little piggy was an H.  And the fourth little
piggy was a newline.

Presently came along David A. Huffman, and made a tree out of the
piggies' frequencies, per the figure below.

           4
       0 /   \
        /     \
       2       \ 1
    0 /  \ 1    \
     /    \      \
    1      1      2
   \n      T      H