@classmethod<EOL><INDENT>def add_sources_argument(cls, group, allow_filters=True, prefix=None, add_root_paths=False):<DEDENT>
prefix = prefix or cls.argument_prefix<EOL>group.add_argument("<STR_LIT>" % prefix,<EOL>action="<STR_LIT:store>", nargs="<STR_LIT:+>",<EOL>dest="<STR_LIT>" % prefix.replace('<STR_LIT:->', '<STR_LIT:_>'),<EOL>help="<STR_LIT>" % prefix)<EOL>if allow_filters:<EOL><INDENT>group.add_argument("<STR_LIT>" % prefix,<EOL>action="<STR_LIT:store>", nargs="<STR_LIT:+>",<EOL>dest="<STR_LIT>" % prefix.replace(<EOL>'<STR_LIT:->', '<STR_LIT:_>'),<EOL>help="<STR_LIT>" % prefix)<EOL><DEDENT>if add_root_paths:<EOL><INDENT>group.add_argument("<STR_LIT>" % prefix,<EOL>action="<STR_LIT:store>", nargs="<STR_LIT:+>",<EOL>dest="<STR_LIT>" % prefix.replace(<EOL>'<STR_LIT:->', '<STR_LIT:_>'),<EOL>help="<STR_LIT>"<EOL>"<STR_LIT>" % prefix)<EOL><DEDENT>
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.