[R] Multi-line input to rsympy

[Joanna Lewis]

Dear R users,

I have been using rsympy to solve a set of simultaneous equations from 
R. There are two solutions for the variable I'm interested in, xx[0] and 
xx[1], which are in terms of symbols called lam and conc. I'd like to 
pick out the one which is positive at (lam=0, conc=0) and call it mysol.

In python I could write:

if (xx[0].subs(lam,0)).subs(conc,0)>0:
  mysol=xx[0]
else:
  mysol=xx[1]

but I'm not sure how to do it from R via rsympy. The various 
combinations of \t and \n characters and spaces I've tried haven't 
worked, and I haven't been able to find any examples online or in the 
help file.

Do you know whether it is possible to enter multi-line input using 
rsympy, and if so how?

Thank you in advance,
Joanna