In many literatures, I can find the definition of the congruence subgrorup $\Gamma_{0}(2)$. It is defined by $\Gamma_{0}(2) = \left \{ \left(\begin{array}{cc} a & b \\ c & d \end{array} \right) \in \text{SL}(2,\mathbb{Z}), \ c\equiv0 \ (\text{mod} \ 2) \right \}$ And its cusp form can be found by SAGE. On the other hand, now I want to consider the different subgroup $\Gamma^{0}(2)$ which is defined by $\Gamma^{0}(2) = \left \{ \left(\begin{array}{cc} a & b \\ c & d \end{array} \right) \in \text{SL}(2,\mathbb{Z}), \ b\equiv0 \ (\text{mod} \ 2) \right \}$ Is there any known cusp forms for this subgp $\Gamma^{0}(2)$? Is it possible to generate them by SAGE? Thank you.