code: def get_found_includes(self, env, scanner, path):
          
          if not scanner:
              return []
          # Clear cached info for this Dir.  If we already visited this
          # directory on our walk down the tree (because we didn't know at
          # that point it was being used as the source for another Node)
          # then we may have calculated build signature before realizing
          # we had to scan the disk.  Now that we have to, though, we need
          # to invalidate the old calculated signature so that any node
          # dependent on our directory structure gets one that includes
          # info about everything on disk.
          self.clear()
          return scanner(self, env, path)
docs: Return this directory's implicit dependencies.
  
          We don't bother caching the results because the scan typically
          shouldn't be requested more than once (as opposed to scanning
          .h file contents, which can be requested as many times as the
          files is #included by other files).