breaking a string in python depending on character pattern

I have a string something like this: ``` a = '5:::{"test":[{"a":1,"b":2},{"a":2,"b":3}]}4:::{"something":[{"d":1,"e":2},{"d":2,"e":3}]}' ``` I would like to split this into a list with the values being: ``` ['5:::{"test":[{"a":1,"b":2},{"a":2,"b":3}]}','4:::{"something":[{"d":1,"e":2},{"d":2,"e":3}]}'] ``` I tried regular expressions like this: ``` b = re.findall(r'[0-9]:::.*(?=[0-9]:::)|(?=$)',a) ``` trying to match parts starting with a digit, followed by three colons, then any character until either a [0-9]::: is hit or the end of the string. This seems completely wrong but I'm at a loss on how to continue here. Thx Markus