Sorry to ask so much questions but I am in hurry. I would like to know why this procedure doesn't work

A= matrix(8,4,(1,1,1,-14,0,1,2,-8,-1,1,1,0,0,0,0,-1,1,0,0,0,0,1,0,0,0,0,0,0,0,1)) b= matrix(8,1,(0,0,0,-1,0,0,0,0)) sign=list('==' '==' '>=' '>=' '>=' '>=' '>=' '>=') x = vector(var('x', n=4, latex_name='x')) B=A*x

p = MixedIntegerLinearProgram(maximization=False, solver = "GLPK") sage: x = p.new_variable(integer=True)

p.add_constraint(B[0] 'sign[0]' b[0])

for the last line I have tryed

```
p.add_constraint(B[0] sign[0] b[0])
p.add_constraint(B[0] == b[0])
```