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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def to_epoch(t):
 """Take a datetime, either as a string or a datetime.datetime object, and return the corresponding epoch"""

    if isinstance(t, str):
        if '+' not in t:
            t = t + '+00:00'
        t = parser.parse(t)
    elif t.tzinfo is None or t.tzinfo.utcoffset(t) is None:
        t = t.replace(tzinfo=pytz.timezone('utc'))

    t0 = datetime.datetime(1970, 1, 1, 0, 0, 0, 0, pytz.timezone('utc'))
    delta = t - t0
    return int(delta.total_seconds())