# Linear programming sum and double sum

I wonder why those syntax are invalid

```
p = MixedIntegerLinearProgram(solver='GLPK')
v = p.new_variable(nonnegative=True)
p.add_constraint(sum([v[i,1] for i in [0,3]) <= 1)
show(p)
```

or

```
p = MixedIntegerLinearProgram(solver='GLPK')
v = p.new_variable(nonnegative=True)
p.add_constraint(sum(sum([v[i,j] for i in [0,3]),for j in [1, 5]) <= 1)
show(p)
```