tools (common/template): add 2 new filters: `timestamp_to_hour` and `delta_to_human`: `timestamp_to_hour` give the hour corresponding to a timestamp, it will be used to display calendar for this time window. `delta_to_human` convert a delta of 2 timestamp to human readable time using `tools.common.date_utils` corresponding function.

from typing import Optional

from twisted.words.xish import domish


class BaseError(Exception):
    namespace: str
    condition: str
    text: Optional[str]
    textLang: Optional[str]
    appCondition: Optional[domish.Element]

class StanzaError(BaseError):
    ...