I'm looking for an arcade expression for arcgis pro symbology. Involves the Asset ID field to symbolise based on text within an asset ID.

Say if the asset ID contains `C2` then blue (for instance), or if the asset ID contains `C1`, `C3` or `GAS`, so on and so forth. 
Imagine a treatment plant with lots of pipes of different colors all based off different common text within the asset ID.

How would the arcade expression look if trying to achieve this?