how do I get a number (seconds or days) from a time interval?

[lostmygithubaccount]

I computed the difference between two timestamp columns in Ibis, resulting in a table like:

┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ open_for                                                                ┃
┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ interval(<IntervalUnit.SECOND: 's'>)                                    │
├─────────────────────────────────────────────────────────────────────────┤
│ <DateOffset: days=0, microseconds=4202000000, months=0, nanoseconds=0>  │
│ <DateOffset: days=0, microseconds=6159000000, months=0, nanoseconds=0>  │
│ <DateOffset: days=0, microseconds=40979000000, months=0, nanoseconds=0> │

how do I then convert this column into an integer/float/number representing seconds (or days, if can have fractions)? attempting to cast this column to "int" or other datatypes tried results in a ConversionException as converting from interval isn't implemented (using the DuckDB backend)

[lostmygithubaccount]

this can be achieved using .epoch_seconds() on the upstream columns and subtracting them

t = t.mutate(time_diff_col = _.time_col_A.epoch_seconds() - _.time_col_B.epoch_seconds())

(thanks to @cpcloud)

[lostmygithubaccount]

related: #6428