New in version 2.0.
True when expr is a LilyPond duration string:
abjad> from abjad.tools import durationtools
abjad> durationtools.is_lilypond_duration_string('4.. * 1/2')
True
Otherwise false:
abjad> durationtools.is_lilypond_duration_string('foo')
False
The regex ^(1|2|4|8|16|32|64|128|\breve|\longa|\maxima)\s*(\.*)\s*(\*\s*(\d+(/\d+)?))?$ underlies this predicate.
Return boolean.