Produce one or more mapping strings for the given property's value.
This is a virtual method, to be overridden by subclasses of Persona who
have linkable properties. Each of their linkable properties should be handled by their implementation of this function, examining the
current value of the property and calling callback with one or more mapping strings for the property's value. Each of these
mapping strings will be added to the IndividualAggregator's link map, related
to the Individual instance which contains this
Persona.
| prop_name |
the name of the linkable property to use, which must be listed in Persona.linkable_properties |
| callback |
a callback to execute for each of the mapping strings generated by this property |
0.1.13