So I have two arrays of hashes:

```
a = [{"b"=>123,"c"=>456}, {"b"=>456,"c"=>555}]
b = [{"c"=>456,"d"=>789},  {"b"=>222,"c"=>444}]

```

How would I concatenate them with the condition that the value of the key `c` is equivalent in both `a` and `b`? Meaning I want to be able to concatenate with the condition of `a['c'] == b['c']`

This is the result I want to get:

```
final_array = [{"b"=>123,"c"=>456,"d"=>789}, {"b"=>456,"c"=>555}, {"b"=>222,"c"=>444}]

```