value_exception.ex

# Hypothetical rewrite of `File.read`
# Not the lack of a `OtherFile.read!` (with a bang),
# but we get the same effect with the caller via `>>>`

# Success
iex> OtherFile.read("./existing_file.txt")
"I'm a little teapot short and stout ..."

# Error
# Note that this returns an Exception struct as a value
# and *does not raise*
iex> OtherFile.read("./missing.file")
%OtherFile.NotFoundError{
  message: "File not found at ./missing.file",
  path: "./missing.file"
}