[\b                             ]*this*,
[(?:(?=\w)(?<!\w)|(?=\W)(?<!\W))]*this*,
[(?:(?<=\w)(?!\w)|(?<=\W)(?!\W))]this*,*
[(?(?=\w)(?<!\w)|(?<!\W))       ]*this*,
[(?(?<=\w)(?!\w)|(?!\W))        ]*this*,*
[(?:(?=\w)(?<!\w)|(?!\w)(?<=\w))]*this*,
[\b                             ],*that*
[(?:(?=\w)(?<!\w)|(?=\W)(?<!\W))]*,*that
[(?:(?<=\w)(?!\w)|(?<=\W)(?!\W))],*that*
[(?(?=\w)(?<!\w)|(?<!\W))       ]*,*that*
[(?(?<=\w)(?!\w)|(?!\W))        ],*that*
[(?:(?=\w)(?<!\w)|(?!\w)(?<=\w))],*that*