// examples :

// things that have a location
joe.location

// things that are people
alice.type == person

// things whose names sounds like 'max': 
fred.name.is('max')

// things whose names starts with 'e' or 'm'
fred.name.startsWith('e') || fred.name.startsWith('m')

// two people that are in the same (known) location
fred.location && fred.location == jane.location && fred.type == person && jane.type == person