def MergeTime(timetuple):
  """Merges a tuple into time as a floating point number.

  @param timetuple: Time as tuple, (seconds, microseconds)
  @type timetuple: tuple
  @return: Time as a floating point number expressed in seconds

  """
  (seconds, microseconds) = timetuple

  assert 0 <= seconds, \
    "Seconds must be larger than or equal to 0, but are %s" % seconds
  assert 0 <= microseconds <= 999999, \
    "Microseconds must be 0-999999, but are %s" % microseconds

  return float(seconds) + (float(microseconds) * 0.000001)