[NTG-context] checking the first word in a command

Dear list, I have the following sample: \starttext \def\Persona{señor Juan Martínez} \def\Persona{señora María Pérez} El/La \Persona\ ha aprobado. \stoptext How can I replace "El/La" in text with a command that can assign the proper article? I could use the translate module, but the real case is more complex than the previous sample. What I need in the command is that it can check the first word in the command \Persona and assign "el" or "la". Which is the right way to do this? Many thanks for your help, Pablo -- http://www.ousia.tk