'Multiply the linear expressions.
Parameters
arg_objs : list
LinExpr for each argument.
size : tuple
The size of the resulting expression.
data :
Additional data required by the atom.
Returns
tuple
(LinOp for objective, list of constraints)'

@staticmethod
def graph_implementation(arg_objs, size, data=None):

    if ((size[0] != 1) and (arg_objs[0].size == (1, 1))):
        arg = lu.promote(arg_objs[0], (size[0], 1))
        arg_objs[0] = lu.diag_vec(arg)
    return (lu.rmul_expr(arg_objs[0], arg_objs[1], size), [])
