def wf_value?(value)
      return true if value.is_a?(Numeric)
      raise Wavefront::Exception::InvalidMetricValue
    end
def wf_value?(value)
      return true if value.is_a?(Numeric)
      raise Wavefront::Exception::InvalidMetricValue
    end
Ensure the given argument is a valid Wavefront value. Can be
 any form of Numeric, including standard notation.

 @param value [Numeric] the source name to validate
 @return True if the value is valid
 @raise Wavefront::Exception::InvalidValue if the value is not valid