Receiving this error
Traceback (most recent call last):
File "<string>", line 2, in <module>
cadabra2.RuntimeException: Can only handle numerical exponents for weight counting.
when running
RicciFull;
drop_weight(_, $field = 3$);
RicciFull has many many terms like
$$h_{b}^{r} h_{d f} h_{e r}+\frac{1}{4}\partial^{b}{h} \partial^{c}{h^{d e}} h_{x}^{f} h^{x}_{c} h_{b}^{r} h_{d f} h_{e}^{s} h_{r s}+\frac{1}{4}\partial^{b}{h^{c d}} \partial_{c}{h^{e f}} h_{x}^{r} h^{x}_{b} h_{d r} h_{e f} $$
Note that
drop_weight(_, $field = 1$)
drop_weight(_, $ field = 3$);
works on a similar (much smaller) expression with the same fields in it.
$$h^{c}_{c}-h^{b c} h_{b c}+h^{b c} h_{b}^{d} h_{c d}-h^{b c} h_{b}^{d} h_{c}^{e} h_{d e}$$