code: def solve(self, dependencies, graceful=True, all_versions=False):  # Ignore PyDocStyleBear
          
  
          def _compare_version_index_url(v1, v2):
              """Get a wrapper around compare version to omit index url when sorting."""
              return compare_version(v1[0], v2[0])
  
          solved = {}
          for dep in self.dependency_parser.parse(dependencies):
              _LOGGER.debug("Fetching releases for: {}".format(dep))
  
              name, releases = self.release_fetcher.fetch_releases(dep.name)
  
              if name in solved:
                  raise SolverException("Dependency: {} is listed multiple times".format(name))
  
              if not releases:
                  if graceful:
                      _LOGGER.info("No releases found for package %s", dep.name)
                  else:
                      raise SolverException("No releases found for package {}".format(dep.name))
  
              releases = [release for release in releases if release in dep]
              matching = sorted(releases, key=cmp_to_key(_compare_version_index_url))
  
              _LOGGER.debug("  matching: %s", matching)
  
              if all_versions:
                  solved[name] = matching
              else:
                  if not matching:
                      solved[name] = None
                  else:
                      if self._highest_dependency_version:
                          solved[name] = matching[-1]
                      else:
                          solved[name] = matching[0]
  
          return solved
docs: Solve `dependencies` against upstream repository.
  
          :param dependencies: List, List of dependencies in native format
          :param graceful: bool, Print info output to stdout
          :param all_versions: bool, Return all matched versions instead of the latest
          :return: Dict[str, str], Matched versions