New in version 2.6.
True when expr is a sequence of Abjad skips:
abjad> from abjad.tools import skiptools
abjad> skips = 3 * skiptools.Skip('s4')
abjad> skips
[Skip('s4'), Skip('s4'), Skip('s4')]
abjad> skiptools.all_are_skips(skips)
True
True when expr is an empty sequence:
abjad> skiptools.all_are_skips([])
True
Otherwise false:
abjad> skiptools.all_are_skips('foo')
False
Return boolean.
Function wraps componenttools.all_are_components().