New in version 2.6.
True when expr is a sequence of Abjad residue class expressions:
abjad> from abjad.tools import sievetools
abjad> sieve = sievetools.ResidueClass(3, 0) | sievetools.ResidueClass(2, 0)
abjad> sieve
{ResidueClass(2, 0) | ResidueClass(3, 0)}
abjad> sievetools.all_are_residue_class_expressions([sieve])
True
True when expr is an empty sequence:
abjad> sievetools.all_are_residue_class_expressions([])
True
Otherwise false:
abjad> sievetools.all_are_residue_class_expressions('foo')
False
Return boolean.