Interactive linear programming

edit

1) According to the documentation of "interactive simplex method" the following code seems legitimate

%display latex A = ([1, 1, 3], [3, 1, 2], [2, 0, 2]) b = (1000, 1500, 1100) c = (10, 5, 2) P = InteractiveLPProblemStandardForm(A, b, c,["x_1", "x_2", "x_3"],slack_variables=["e_4", "e_5", "e_6"], problem_type="min",constraint_type=["<=", ">=","<="]) show(P)

seems correct. But I receive an error message

TypeError: __init__() got an unexpected keyword argument 'constraint_type'.

2) mai I write "=" 3) If I add

variable_type=[">=", ">="]

what must I enter if there is no restriction on a variable ?