Im 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 acheive this?

hope i have explained that right.