I currently have a pre-defined dictionary (ignore the letters). I want the conversions to be more robust, though. Say 33000000 microseconds gets inputted and knows to convert to 33 seconds. Then any microsecond input over a minute, but under an hour shows as minutes, etc. Is it possible to get this coded without needing this pre-defined dictionary? Preferably a function that takes in a microsecond input and then outputs the proper conversion. 

```
'A100.txt'                          :'100 us',
'B500.txt'                          :'500 us',
'C1000.txt'                         :'1 ms',
'D4000.txt'                         :'4 ms',
'E5000.txt'                         :'10 ms',
'F30000.txt'                        :'30 ms',
'G100000.txt'                       :'100 ms',
'H300000.txt'                       :'300 ms',
'I1000000.txt'                      :'1 sec',
'J3000000.txt'                      :'3 secs',
'K10000000.txt'                     :'10 secs',
'L30000000.txt'                     :'30 secs',
'M60000000.txt'                     :'1 min',
'N180000000.txt'                    :'3 mins',
'O600000000.txt'                    :'10 mins',
'P1800000000.txt'                   :'30  mins',
'Q3600000000.txt'                   :'1 hr',
'R7200000000.txt'                   :'2 hrs',
'S14400000000.txt'                  :'4 hrs'}

```