SHA256File returns the SHA-256 digest of a file's contents as lowercase
hexadecimal, copying the file through the hash in chunks so its size does not
matter. Comes with a doc comment and table-driven tests. (closes#19)
Model: opus-5
FileExists reports whether a path holds a regular file and DirExists whether it
holds a directory, both answering false for anything they cannot look at.
Comes with doc comments and table-driven tests. (closes#15)
Model: opus-5