saving the cppheaderparser output as valid json - json

Question

the python program
http://sourceforge.net/projects/cppheaderparser/
can parse a c++ header file and store the info (about classes etc) in a python dictionary.
Using the included example program readSampleClass.py and
data_string = ( repr(cppHeader) )
with open('data.txt', 'w') as outfile:
json.dumps(data_string,outfile)
it saved the output but it is not valid json as
it uses single, not double quotes and key part is not quoted.
sample of output: (reduced)
{'enums': [], 'variables': [], 'classes':
{'SampleClass':
{'inherits': [], 'line_number': 8, 'declaration_method': 'class', 'typedefs':
{'public': [], 'private': [], 'protected': []
}, 'abstract': False, 'parent': None,'parent': None, 'reference': 0, 'constant': 0, 'aliases': [], 'raw_type': 'void', 'typedef': None, 'mutable': False
}], 'virtual': False, 'rtnType': 'int', 'returns_class': False, 'name': 'anotherFreeFunction', 'constructor': False, 'inline': False, 'returns_pointer': 0, 'defined': False
}]
}
so the question is:
How can I make it use double quotes and not single and how can I also make it quote the value part. Like False in sample.
I assume is possible as the creator of cppheaderparser wrote
about json.dumps(repr(cppHeader))
https://twitter.com/senexcanis/status/559444754166198272
Why use the json lib if its not valid jason?
That said I have never used python before and it might just not work as i think.
-update-
After some json doc reading, i gave up on json.dump as it seems to do nothing to the output in this case.
I ended up doing
data_string = ( repr(cppHeader) )
data_string = string.replace(data_string,'\'', '\"')
data_string = string.replace(data_string,'False', '\"False\"')
data_string = string.replace(data_string,'True', '\"True\"')
data_string = string.replace(data_string,'None', '\"None\"')
data_string = string.replace(data_string,'...', '')
with open('data.txt', 'w') as outfile:
outfile.write (data_string)
which give valid json - at least for my test c++ headers.
-update 2-
The creator of cppheaderparse just released a new 2.6 version where its possible to write CppHeaderParser.CppHeader("yourHeader.h").toJSON() to save as json.