I have a cluster fasta file (called file) which looks like:
```
>1AB2
>1AB2 AA
NWWIEUNJRNIBGOWNGIOWGRBIGBRGRIOWGI
NCIDHFR8EHGBVPIWOBGIGRI
>1AB3 AA
WNIOREHUEBRGOUERGHBERGIORBGREUGEGO
NWFWRUBGREOUEREOBRIOBNERIOBN
>1SC4 AA
WNIOREHUEBRGOUERGHBERGIORBGREUGEGO
NWFWRUBGREOUEREOBRIOBNERIOBN
>2CD5 AA
WNIOREHUEBRGOUERGHBERGIORBGREUGEGO
NWFWRUBGREOUEREOBRIOBNERIOBN
>2AC6
>2AC6 AA
NFIGEURHGEIROHEGHTUTJGENLJBBEOWRIU
NFIROUHBOERVERUGBERUOVREOIBROEBVUE
NVHIRE
>2ONM AA
BUCIEHBUORBREOBWQVURVELLAJFLHIEBGR
NHEIBVEURIGBVNRIHEOEAJVSJDNHVUGBVR
NEBIBVVBRU
>2POD AA
BUFEWIBOEUWBWOREBRIUBGUERIGBVOSRIP
BUEIBVEO
>7KZL
>7KZL AA
BUIREBVAUREVBREOIRGPNJBFDVERUBVROR
>6HG3
>6GH3 AA
NBVUIREVOIAWRHRUGRTYUVDNJKDFHUGSEI
FHUIERBLUUIREB
>6GH4 AA
BDFUIGEVUERERHOBERIHBSDLKFJBNIERIH
NFHILRUGAURHG
```
the file has 4 groups: `1AB2, 2AC6, 7KZL, and 6GH3`. the content during the first `>1AB2` and the first `>2AC6` belongs to the cluster `1AB2`. the content during the first `>2AC6` and the first `>7KZL` belongs to the cluster `2AC6`. 

I want to separate the file into 4 files at the second `>XXXX`. each file should look like:

file_1
```
>1AB2 AA
NWWIEUNJRNIBGOWNGIOWGRBIGBRGRIOWGI
NCIDHFR8EHGBVPIWOBGIGRI
>1AB3 AA
WNIOREHUEBRGOUERGHBERGIORBGREUGEGO
NWFWRUBGREOUEREOBRIOBNERIOBN
>1SC4 AA
WNIOREHUEBRGOUERGHBERGIORBGREUGEGO
NWFWRUBGREOUEREOBRIOBNERIOBN
>2CD5 AA
WNIOREHUEBRGOUERGHBERGIORBGREUGEGO
NWFWRUBGREOUEREOBRIOBNERIOBN
```
file_2
```
>2AC6 AA
NFIGEURHGEIROHEGHTUTJGENLJBBEOWRIU
NFIROUHBOERVERUGBERUOVREOIBROEBVUE
NVHIRE
>2ONM AA
BUCIEHBUORBREOBWQVURVELLAJFLHIEBGR
NHEIBVEURIGBVNRIHEOEAJVSJDNHVUGBVR
NEBIBVVBRU
>2POD AA
BUFEWIBOEUWBWOREBRIUBGUERIGBVOSRIP
BUEIBVEO
```
file_3
```
>7KZL AA
BUIREBVAUREVBREOIRGPNJBFDVERUBVROR
```
file_4
```
>6GH3 AA
NBVUIREVOIAWRHRUGRTYUVDNJKDFHUGSEI
FHUIERBLUUIREB
>6GH4 AA
BDFUIGEVUERERHOBERIHBSDLKFJBNIERIH
NFHILRUGAURHG
```