in spectator/common_tags.py [0:0]
def _add_non_empty(tags: Dict[str, str], tag: str, *env_vars: str) -> None:
for env_var in env_vars:
value = os.environ.get(env_var)
if value is None:
continue
value = value.strip()
if len(value) != 0:
tags[tag] = value
break