def wf_epoch?(timestamp)
      return true if timestamp.is_a?(Numeric)
      raise Wavefront::Exception::InvalidTimestamp
    end
def wf_epoch?(timestamp)
      return true if timestamp.is_a?(Numeric)
      raise Wavefront::Exception::InvalidTimestamp
    end
Ensure the given argument is a valid epoch timestamp. Again,
 no range checking.

 @param timestamp [String, Integer]
 @return True if the timestamp is valid
 @raise Wavefront::Exception::InvalidMaintenanceWindow