Most arguments should be keyword-only

[simonbowly]

Especially with pd_add_constrs, positional arguments lb, ub, vtype, name get unwieldy. There is less chance for confusion if we make these keyword only. So we will go with:

accessor.pd_add_vars(model, *, lb, ub, vtype, name=None)
accessor.pd_add_constrs(model, lhs, sense, rhs, *, name)

i.e. attributes must be specified by keyword, the model is always the first positional argument, and essential arguments for constraints are left -> right positional.

[simonbowly]

Done. Attribute and name arguments are keyword-only for:

• pd_add_vars
• pd.Index.grb.pd_add_vars
• pd.DataFrame.grb.pd_add_vars

name is keyword only (lhs, sense, rhs positional) for:

• pd_add_constrs
• pd.DataFrame.grb.pd_add_constrs