Fix style violations in commit 4a90bd4, small changes

Fix style violations in commit 4a90bd4, small changes

- Commit 4a90bd4 contained a rather large number of style violations:
  - Indentation/sequence formatting
  - Wrapping of long lines
  - Docstrings whose first line was wrapped
  - A stray backslash in a docstring
- opcodes: Don't check for list or tuple. None of the other opcodes does
  it explicitely. As long as the length and the items match the value is
  accepted.
- server/noded: “if variable” doesn't test for None, but False

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>