Create a dummy conditional on two other variables

#1
Hello there,

I have data on European Union membership in the form of a dummy variable were eu_o = Origin is a member, eu_d=Destination is a member. I want to create another dummy variable that takes the value of 1 if both eu_o=eu_d=1. Is there a command to do this?
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#2
How many categories do you have? If you have 3 categories, you need 2 indicator variables. If you have 4 categories, you need 3 indicator variables.