def FloatingPointTimestamp(microseconds_since_the_epoch, zero_value=None):
  """Converts microseconds since the epoch to seconds since the epoch, or None for -1 or 0.

  Args:
    microseconds_since_the_epoch: int
  Returns:
    float|None
  """
  if microseconds_since_the_epoch == -1:
    return zero_value
  return (microseconds_since_the_epoch // 10**6) + ((microseconds_since_the_epoch % 10**6) / 1e6)