Used mainly for computing the cuspidal subspace of modular symbols.
The module modular.modsym.boundary defines the following classes:
This class is an abstract base class, so only derived classes should be instantiated.
INPUT: weight - int, the weight group - congroup.CongruenceGroup, a congruence subgroup. sign - int, either -1, 0, or 1 base_field - rings.Ring (defaults to the rational numbers)