def resolve(self, root_reqs, check_supported_wheels):
        # type: (List[InstallRequirement], bool) -> RequirementSet
        """Resolve what operations need to be done

        As a side-effect of this method, the packages (and their dependencies)
        are downloaded, unpacked and prepared for installation. This
        preparation is done by ``pip.operations.prepare``.

        Once PyPI has static dependency metadata available, it would be
        possible to move the preparation to become a step separated from
        dependency resolution.
        """
        requirement_set = RequirementSet(
            check_supported_wheels=check_supported_wheels
        )
        for req in root_reqs:
            requirement_set.add_requirement(req)

        # Actually prepare the files, and collect any exceptions. Most hash
        # exceptions cannot be checked ahead of time, because
        # _populate_link() needs to be called before we can make decisions
        # based on link type.
        discovered_reqs = []  # type: List[InstallRequirement]
        hash_errors = HashErrors()
        for req in chain(root_reqs, discovered_reqs):
            try:
                discovered_reqs.extend(self._resolve_one(requirement_set, req))
            except HashError as exc:
                exc.req = req
                hash_errors.append(exc)

        if hash_errors:
            raise hash_errors

        return requirement_set
Resolve what operations need to be done

        As a side-effect of this method, the packages (and their dependencies)
        are downloaded, unpacked and prepared for installation. This
        preparation is done by ``pip.operations.prepare``.

        Once PyPI has static dependency metadata available, it would be
        possible to move the preparation to become a step separated from
        dependency resolution.
        
product/gradle-plugin/src/main/python/pip/_internal/resolution/legacy/resolver.py