The rgb function is incomplete. Complete it so that passing in RGB decimal values will result in a hexadecimal representation being returned. Valid decimal values for RGB are 0 - 255. Any values that fall out of that range must be rounded to the closest valid value.
Note: Your answer should always be 6 characters long, the shorthand with 3 will not work here.
The following are examples of  expected output values:
```python
rgb(255, 255, 255) # returns FFFFFF
rgb(255, 255, 300) # returns FFFFFF
rgb(0,0,0) # returns 000000
rgb(148, 0, 211) # returns 9400D3
```
```if:nasm
char \*rgb(int r, int g, int b, char \*outp)
```
def rgb(r, g, b): 
    return ''.join(['%02X' % max(0, min(x, 255)) for x in [r, g, b]])
def rgb(r, g, b): 
    return ''.join(['%02X' % max(0, min(x, 255)) for x in [r, g, b]])