Tables have contains proc, as well as arrays, seqs, openarrays, and other data
structures.
if myTable.contains(myKey) or mySeq.contains(myKey):
That said, there's a in and notin operators in nim which translate to the
underlying contains call. So you can implement contains proc for your own data
structure and in and notin will just work for it.
if myKey in myTable and myKey notin mySeq:
That said, contains proc for array-like structures is linear complexity. For
big datasets you likely want to use HashSet instead.
