docs: def sync_sources(self, force=False):
          """Sync in only the sources.csv file"""
          from ambry.orm.file import File
  
          self.dstate = self.STATES.BUILDING
  
          synced = 0
  
          for fc in [File.BSFILE.SOURCES]:
              bsf = self.build_source_files.file(fc)
              if bsf.fs_is_newer or force:
                  self.log('Syncing {}'.format(bsf.file_name))
                  bsf.fs_to_objects()
                  synced += 1
  
          return synced