New in version 2.0.
Generate all restricted growth functions of length in lex order:
abjad> from abjad.tools import sequencetools
abjad> for rgf in sequencetools.yield_all_restricted_growth_functions_of_length(4):
... rgf
...
(1, 1, 1, 1)
(1, 1, 1, 2)
(1, 1, 2, 1)
(1, 1, 2, 2)
(1, 1, 2, 3)
(1, 2, 1, 1)
(1, 2, 1, 2)
(1, 2, 1, 3)
(1, 2, 2, 1)
(1, 2, 2, 2)
(1, 2, 2, 3)
(1, 2, 3, 1)
(1, 2, 3, 2)
(1, 2, 3, 3)
(1, 2, 3, 4)
Return generator of tuples.