gistfile1.txt

# Directory structure
.
├── README.md
└── lib
    ├── a.rb
    ├── b.rb
    └── c.rb

# Blob SHAs:
README.md's SHA is 86f7e437faa5a7fce15d1ddcb9eaeaea377667b8
 lib/a.rb's SHA is e9d71f5ee7c92d6dc9e92ffdad17b8bd49418f98
 lib/b.rb's SHA is 84a516841ba77a5b4648de2cd0dfcb30ea46dbb4
 lib/c.rb's SHA is 3c363836cf4e16666669a25da280a1865c2d2874

# lib/ tree contents (this is a single three-line string):
100644 blob e9d71f5ee7c92d6dc9e92ffdad17b8bd49418f98 a.rb
100644 blob 84a516841ba77a5b4648de2cd0dfcb30ea46dbb4 b.rb
100644 blob 3c363836cf4e16666669a25da280a1865c2d2874 c.rb

# Get the lib/ tree SHA by running the SHA function on the lib/ tree contents string
SHA("100644 blob e9d71f5...") = 8a32db017de1bbb8d323f38c7c483bccffa915ed

# root tree contents (this is a single two-line string):
100644 blob 86f7e437faa5a7fce15d1ddcb9eaeaea377667b8 README.md
040000 tree 8a32db017de1bbb8d323f38c7c483bccffa915ed lib

# Get the root tree SHA by running the SHA function on the root tree contents string
SHA("10644 blob 86f7e43..." = 0f120cd8a791f9b752d57d903cea58f4bc3828b1