In Python, I have a dataframe that has json variables.

For example, if keys and values of a column are like:

```
{'a': 3, 'b': 2, 'c': 1}
{'d': 287, 'e': 56, 'f': 17, 'g': 9}
{'h': 22, 'i': 15, 'a': 7}
{'g': 17, 'd': 15, 'e': 15, 'f': 7, 'h': 15}

```

I want to append columns to be like

```none
key_1 value_1 key_2 value_2 key_3 value_3 key_4 value_4 key_5 value_5
a      3       b      2       c      1
d      287     e      56      f      17     g      9
h      22      i      15      a       7       
g      17      d      15      e      15     f      7      h      15

```

i.e.,

1. One pair generates two columns. (key\_, value\_)
2. Each row has different numbers of key-value pairs.
3. Though keys are the same, the values of the keys can be different.
4. Though keys are different, the values of the keys can be the same.
5. I need to make only up to 600 columns (300 pairs \* 2).