How to use interpolate operator to define problem

General Discussion
1

Now, we need to difine bilinear form like this: ((id - I_{h})\nable p_h,(id - I_{h})\nable q_h)
p_h , q_h \in fespace(Th,P2)
I_{h} is interpolate operator to fespace(Th,P1);

define problem as follows:
mesh Th = square(16,16);
fespace Vh (Th,P2);
fespace Mh(Th,P1);
matrix interMx = interpolate(Mh,Vh,op = 1);//dx
matrix interMy = interpolate(Mh,Vh,op=2);//dy

problem pressure(p_h, q_h)
int2d(Th)(dx(p_h) * dx(q_h) + dy(p_h) * dy(q_h) )
+int2d(Th)((interMx * p_h) * (interMx * q_h) + (interMy * p_h) * (interMy * q_h) )
-int2d(Th)( dx(p_h) * (interMx * q_h) + dy(p_h) * (interMy * q_h))
-int2d(Th)( dx(q_h) * (interMx * p_h) + dy(q_h) * (interMy * p_h))

when try to run this code, some compile error ocuring
can we define this problem, or using matrix formulations