New in version 2.6.
True when expr is a sequence of Abjad tuplets:
abjad> tuplet = Tuplet((2, 3), "c'8 d'8 e'8")
abjad> tuplettools.all_are_tuplets([tuplet])
True
True when expr is an empty sequence:
abjad> tuplettools.all_are_tuplets([])
True
Otherwise false:
abjad> tuplettools.all_are_tuplets('foo')
False
Return boolean.
Function wraps componenttools.all_are_components().