import vcsn c = vcsn.context('lal_char, q')
Note that left-scalar product and right-scalar product are very different: the left-scalar product changes the weights in the polynomials, while the right-scalar product changes the expressions.
e = c.expression('<2>a<3>bc', 'none') x = e.expansion() e
x.rweight(w), you may write
x * w.
x * c.weight('4')
You may even run the simpler:
x * 4
The expansion of a scalar product is the scalar product of the expansion: