code: def set_objective(self, expression):
          
  
          if isinstance(expression, numbers.Number):
              # Allow expressions with no variables as objective,
              # represented as a number
              expression = Expression(offset=expression)
  
          # Clear previous objective
          for i in range(swiglpk.glp_get_num_cols(self._p)):
              swiglpk.glp_set_obj_coef(self._p, 1 + i, 0)
  
          for variable, value in expression.values():
              var_index = self._variables[variable]
              swiglpk.glp_set_obj_coef(self._p, var_index, float(value))
  
          swiglpk.glp_set_obj_coef(self._p, 0, float(expression.offset))
docs: Set objective of problem.