@classmethod<EOL><INDENT>def get_startup_sequence(cls, rcfile, norc, stdin, command):<DEDENT>
raise NotImplementedError<EOL>
Return a dict containing:
- 'stdin': resulting stdin setting.
- 'command': resulting command setting.
- 'do_rcfile': True if a file should be sourced directly.
- 'envvar': Env-var that points at a file to source at startup. Can be None.
- 'files': Existing files that will be sourced (non-user-expanded), in source
    order. This may also incorporate rcfile, and file pointed at via envvar.
    Can be empty.
- 'bind_files': Files to inject Rez binding into, even if that file doesn't
    already exist.
- 'source_bind_files': Whether to source bind files, if they exist.