Método de Euler en Python usando Sage

El clásico método de Euler(en Python):
La clase...

class ForwardEuler:
    def __init__(self, f, dt):
        self.f, self.dt = f, dt
    
    def set_initial_condition(self, u0, t0=0):
        self.u = []        
        self.t = []
        self.u.append(float(u0))
        self.t.append(float(t0))
        self.k = 0 
    
    def solve(self, T):
        tnew = 0
        while tnew <= T:
            unew = self.advance()
            self.u.append(unew)
            tnew = self.t[-1] + self.dt
            self.t.append(tnew)
            self.k += 1
        return numpy.array(self.u), numpy.array(self.t)
    
    def advance(self):
        u, dt, f, k, t = \
            self.u, self.dt, self.f, self.k, self.t[-1]
        unew = u[k] + dt*f(u[k], t)
        return unew

Utilizando la clase:

def _f1(u, t):
    return 0.2*u*(1-u)
 
u0 = 0.1
dt = 0.1
T = 40
method = ForwardEuler(_f1, dt)
method.set_initial_condition(u0, 0)
u, t = method.solve(T)
  
g1=line([[t[i],u[i]] for i in range(len(u))],rgbcolor=(1/4,1/8,3/4))
g2 = text("Ec. Log.", (20, 1))
g = g1+g2
show(g, xmin=0, xmax=41, ymin=0, ymax=1)