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from datetime import datetime, timezone, tzinfo
def datetime_exists(dt):
"""Check if a datetime exists. Taken from: https://pytz-deprecation-shim.readthedocs.io/en/latest/migration.html"""
# There are no non-existent times in UTC, and comparisons between
# aware time zones always compare absolute times; if a datetime is
# not equal to the same datetime represented in UTC, it is imaginary.
return dt.astimezone(timezone.utc) == dt
def datetime_ambiguous(dt: datetime):
"""Check whether a datetime is ambiguous. Taken from: https://pytz-deprecation-shim.readthedocs.io/en/latest/migration.html"""
# If a datetime exists and its UTC offset changes in response to
# changing `fold`, it is ambiguous in the zone specified.
return datetime_exists(dt) and (
dt.replace(fold=not dt.fold).utcoffset() != dt.utcoffset()
)
def valid_datetime(dt):
"""Returns True if the datetime is not ambiguous or imaginary, False otherwise."""
if isinstance(dt.tzinfo, tzinfo) and not datetime_ambiguous(dt):
return True
return False
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