Programmatically create a custom permission level in sharepoint

public void CreateCustomPermissionLevel()

        {

            try

            {

                using (SPSite site = new SPSite(SPContext.Current.Site.Url))

                {

                    using (SPWeb web = site.OpenWeb())

                    {

                        SPRoleDefinition role = new SPRoleDefinition();

                        role.Name = "CustomRole_Add_Edit";

                        role.Description = "Description: Custom Permission level";

                        role.BasePermissions =

                                               SPBasePermissions.AddAndCustomizePages |

                                               SPBasePermissions.ApplyStyleSheets |

                                               SPBasePermissions.AddListItems |

                                               SPBasePermissions.EditListItems |

                                               SPBasePermissions.ViewListItems |

                                               SPBasePermissions.OpenItems |

                                               SPBasePermissions.ViewVersions |

                                               SPBasePermissions.CreateAlerts |

                                               SPBasePermissions.ViewPages;

                        web.RoleDefinitions.Add(role);

                    }

                }

            }

            catch (Exception ex)

            {

              

            }

        }