sage-flatsurf: Flat Surfaces in Sage. We aim for this package to support the investigation of geometric, algebraic and dynamical questions related to flat surfaces. By flat surface we mean a surface modeled on the plane with monodromy given by similarities of the plane, though current efforts are focused on translation surfaces and half-translation surfaces. Currently, the package can generate images of flat surfaces, plot straight-line trajectories, deform surfaces through the SL(2,R) action, and compute Delaunay decompositions. SageMath is used to perform exact arithmetic