code: def add_sources_argument(cls, group, allow_filters=True, prefix=None, add_root_paths=False):
          
          prefix = prefix or cls.argument_prefix
  
          group.add_argument("--%s-sources" % prefix,
                             action="store", nargs="+",
                             dest="%s_sources" % prefix.replace('-', '_'),
                             help="%s source files to parse" % prefix)
  
          if allow_filters:
              group.add_argument("--%s-source-filters" % prefix,
                                 action="store", nargs="+",
                                 dest="%s_source_filters" % prefix.replace(
                                     '-', '_'),
                                 help="%s source files to ignore" % prefix)
  
          if add_root_paths:
              group.add_argument("--%s-source-roots" % prefix,
                                 action="store", nargs="+",
                                 dest="%s_source_roots" % prefix.replace(
                                     '-', '_'),
                                 help="%s source root directories allowing files "
                                      "to be referenced relatively to those" % prefix)
docs: Subclasses may call this to add sources and source_filters arguments.
  
          Args:
              group: arparse.ArgumentGroup, the extension argument group
              allow_filters: bool,  Whether the extension wishes to expose a
                  source_filters argument.
              prefix: str, arguments have to be namespaced.