Unparse duration in ISO 8601 format?

[kennyjwilli]

It appears the only way to format a duration is using the unparse-duration function which returns a string with an implicit format.

(time-fmt/unparse-duration (time/period :hours 1))
=> "1 hour"

Is there a way to configure the formatting for a duration to output a ISO 8601 string? It uses the format PnYnMnDTnHnMnS for formatting a duration to a string.