timespan_2_starts_when_timespan_1_starts

abjad.timespans.timespan_2_starts_when_timespan_1_starts.timespan_2_starts_when_timespan_1_starts(timespan_1=None, timespan_2=None, hold=False)

Makes time relation indicating that timespan_2 starts when timespan_1 starts.

>>> relation = abjad.timespans.timespan_2_starts_when_timespan_1_starts()
>>> abjad.f(relation)
abjad.timespans.TimespanTimespanTimeRelation(
    inequality=abjad.timespans.CompoundInequality(
        [
            abjad.TimespanInequality('timespan_1.start_offset == timespan_2.start_offset'),
            ],
        logical_operator='and',
        ),
    )

Returns time relation or boolean.