How to use the libceed.BASIS_COLLOCATED function in libceed

os.path.join(file_dir, "test-qfunctions.h:setup_mass_2d"))
  qf_setup_tet.add_input("weights", 1, libceed.EVAL_WEIGHT)
  qf_setup_tet.add_input("dx", dim*dim, libceed.EVAL_GRAD)
  qf_setup_tet.add_output("rho", 1, libceed.EVAL_NONE)

  qf_mass_tet = ceed.QFunction(1, qfs.apply_mass,
                               os.path.join(file_dir, "test-qfunctions.h:apply_mass"))
  qf_mass_tet.add_input("rho", 1, libceed.EVAL_NONE)
  qf_mass_tet.add_input("u", 1, libceed.EVAL_INTERP)
  qf_mass_tet.add_output("v", 1, libceed.EVAL_INTERP)

  # Operators
  op_setup_tet = ceed.Operator(qf_setup_tet)
  op_setup_tet.set_field("weights", rxi_tet, bx_tet, libceed.VECTOR_NONE)
  op_setup_tet.set_field("dx", rx_tet, bx_tet, libceed.VECTOR_ACTIVE)
  op_setup_tet.set_field("rho", rui_tet, libceed.BASIS_COLLOCATED,
                         qdata_tet)

  op_mass_tet = ceed.Operator(qf_mass_tet)
  op_mass_tet.set_field("rho", rui_tet, libceed.BASIS_COLLOCATED, qdata_tet)
  op_mass_tet.set_field("u", ru_tet, bu_tet, libceed.VECTOR_ACTIVE)
  op_mass_tet.set_field("v", ru_tet, bu_tet, libceed.VECTOR_ACTIVE)

  ## ------------------------- Hex Elements -------------------------

  # Restrictions
  indx_hex = np.zeros(nelem_hex*p_hex*p_hex, dtype="int32")
  for i in range(nelem_hex):
    col = i % nx_hex;
    row = i // nx_hex;
    offset = (nx_tet*2+1)*(ny_tet*2)*(1+row)+col*2

os.path.join(file_dir, "test-qfunctions.h:setup_mass"))
  qf_setup.add_input("weights", 1, libceed.EVAL_WEIGHT)
  qf_setup.add_input("dx", 1, libceed.EVAL_GRAD)
  qf_setup.add_output("rho", 1, libceed.EVAL_NONE)

  qf_mass = ceed.QFunction(1, qfs.apply_mass,
                           os.path.join(file_dir, "test-qfunctions.h:apply_mass"))
  qf_mass.add_input("rho", 1, libceed.EVAL_NONE)
  qf_mass.add_input("u", 1, libceed.EVAL_INTERP)
  qf_mass.add_output("v", 1, libceed.EVAL_INTERP)

  # Operators
  op_setup = ceed.Operator(qf_setup)
  op_setup.set_field("weights", rxi, bx, libceed.VECTOR_NONE)
  op_setup.set_field("dx", rx, bx, libceed.VECTOR_ACTIVE)
  op_setup.set_field("rho", rui, libceed.BASIS_COLLOCATED,
                     libceed.VECTOR_ACTIVE)

  op_mass = ceed.Operator(qf_mass)
  op_mass.set_field("rho", rui, libceed.BASIS_COLLOCATED, qdata)
  op_mass.set_field("u", ru, bu, libceed.VECTOR_ACTIVE)
  op_mass.set_field("v", ru, bu, libceed.VECTOR_ACTIVE)

  # Setup
  op_setup.apply(x, qdata)

  # Apply mass matrix
  u.set_value(0)
  op_mass.apply(u, v)

  # Check
  v_array = v.get_array_read()