Options = object
  targets*: seq[Target]
  format*: string            ## `text` or `github`.
  help*: bool                ## `--help` or `-h` was given.

Target = object
  path*: string              ## A file or a glob pattern.
  lines*: seq[tuple[first, last: int]] ## Empty means the whole file.

helpText = """Usage: linter [options] [target...]

Lint the files selected by the config's `sources`, or the targets given on the
command line.

Targets:
  path/to/file.nim        a single file
  path/to/dir             a directory, linted recursively
  path/to/dir/*.nim       a glob pattern, expanded by Lint
  path/to/file.nim:10-12  a file, restricted to line ranges

  Targets replace the config's `sources` and every `ignoredPatterns`, including
  step-level ones. Quote glob patterns so the shell does not expand them first.

  Glob patterns are always written in UNIX form, with `/` as the separator, even
  on Windows.

Options:
  --format=text           human-readable report (default)
  --format=github         GitHub Actions workflow commands, for inline
                          annotations on a pull request
  -h, --help              show this message and exit

Exit codes:
  0  no errors; hints may still have been reported
  1  at least one finding was reported as an error
  2  a source file could not be parsed
  3  nothing to lint: no file matched the sources or the targets
  4  a check raised an exception
"""