It returns the difference of integers.
Input  Output 

{"a":0,"b":0}

0

{"a":1,"b":0}

1

{"a":2,"b":5}

7

{"a":2,"b":5}

3

It returns the difference of floats.
Input  Output 

{"a":0.5,"b":0.5}

0

{"a":1.3,"b":0.3}

1.6

{"a":1.5,"b":0.8}

0.7
