'Indicates if a warning (based on the time it occurred and its type)
is a valid warning. A warning is considered "invalid" if this type of
warning was marked as "disabled" at the time the warning occurred.'

def is_valid(self, timestamp, warning_type):

    disabled_intervals = self.disabled_warnings.get(warning_type, [])
    for (start, end) in disabled_intervals:
        if ((timestamp >= start) and ((end is None) or (timestamp < end))):
            return False
    return True
