$ coverage combine --help
Usage: coverage combine [options] <path1> <path2> ... <pathN>
Combine data from multiple coverage files collected with 'run -p'. The
combined results are written to a single file representing the union of the
data. The positional arguments are data files or directories containing data
files. If no paths are provided, data files in the default data file's
directory are combined.
Options:
-a, --append Append coverage data to .coverage, otherwise it starts
clean each time.
--keep Keep combined coverage files, otherwise they are deleted.
--debug=OPTS Debug options, separated by commas. [env: COVERAGE_DEBUG]
-h, --help Get help on this command.
--rcfile=RCFILE Specify configuration file. By default '.coveragerc',
'setup.cfg', 'tox.ini', and 'pyproject.toml' are tried.
[env: COVERAGE_RCFILE]