<code python>
import time

#pattern = "%a %b %d %H:%M:%S  %Y"
pattern = '%Y-%m-%d %H:%M:%S'
date_time = '2007-02-05 16:15:18'

epoch = int(time.mktime(time.strptime(date_time, pattern)))
print epoch
</code>

<code python>
def delta_time(dt, delta, fmt='%Y-%m-%d %H:%M:%S'):
    """
    Adds a time delta to a datetime object with a specific format.

    Example of call:
    >>> new_dt = delta_time('2012-10-27 12:05:54', datetime.timedelta(minutes=45))
    >>> print("%s:%s:%s" % (new_dt.hour, new_dt.minute, new_dt.second))
    12:50:54
    """
    return datetime.datetime(*time.strptime(dt, fmt)[:6]) + delta
</code>