log/field.go
func Float64(key string, val float64) Field {
	return Field{
		key:        key,
		fieldType:  float64Type,
		numericVal: int64(math.Float64bits(val)),
	}
}
func Float64(key string, val float64) Field {
	return Field{
		key:        key,
		fieldType:  float64Type,
		numericVal: int64(math.Float64bits(val)),
	}
}
func Float64 ( key string , val float64 ) Field { return Field { key : key , fieldType : float64Type , numericVal : int64 ( math . Float64bits ( val ) ) , } }
// Float64 adds a float64-valued key:value pair to a Span.LogFields() record
Float64 adds a float64 - valued key : value pair to a Span . LogFields () record