title: fenics did not show figure . NameError: name interactive is not defined
body: <p>I installed fenics on windows subsystem for linux to do my homework.I am trying to test fenics. So I use ft01_possion.py on the tutorial. </p>
  
  <pre><code>from fenics import *
  
  # Create mesh and define function space
  mesh = UnitSquareMesh(8, 8)
  V = FunctionSpace(mesh, 'P', 1)
  
  # Define boundary conditions
  u_D = Expression('1 + x[0]*x[0] + 2*x[1]*x[1]', degree = 2)
  
  def boundary(x, on_boundary):
        return on_boundary
  
  bc = DirichletBC(V, u_D, boundary)
  
  # Define variational problem
  u = TrialFunction(V)
  v = TestFunction(V)
  f = Constant(-6.0)
  a = dot(grad(u), grad(v))*dx
  L = f*v*dx
  
  # Compute solution
  u = Function(V)
  solve(a == L, u, bc)
  
  # Plot solution and mesh
  plot(u)
  plot(mesh)
  interactive()
  </code></pre>
  
  <p>It did not show the figure.
  the error i am getting is:</p>
  
  <pre><code>Solving linear variational problem.
  Traceback (most recent call last):
  File "ft01_poisson.py", line 29, in &lt;module&gt;
  interactive()
  NameError: name 'interactive' is not defined
  </code></pre>
  
  <p>I have tried to reinstall the newest version of fenics without success.</p>
  
  <p>While the print out of the error values work, the NameError prevents the plots from being shown.</p>