code: def _get_dependencies_from_cache(ireq):
      
      if os.environ.get("PASSA_IGNORE_LOCAL_CACHE"):
          return
      if ireq.editable:
          return
      try:
          deps = DEPENDENCY_CACHE[ireq]
          pyrq = REQUIRES_PYTHON_CACHE[ireq]
      except KeyError:
          return
  
      # Preserving sanity: Run through the cache and make sure every entry if
      # valid. If this fails, something is wrong with the cache. Drop it.
      try:
          packaging.specifiers.SpecifierSet(pyrq)
          ireq_name = packaging.utils.canonicalize_name(ireq.name)
          if any(_is_cache_broken(line, ireq_name) for line in deps):
              broken = True
          else:
              broken = False
      except Exception:
          broken = True
  
      if broken:
          print("dropping broken cache for {0}".format(ireq.name))
          del DEPENDENCY_CACHE[ireq]
          del REQUIRES_PYTHON_CACHE[ireq]
          return
  
      return deps, pyrq
docs: Retrieves dependencies for the requirement from the dependency cache.