code: def target_types_from_build_file_aliases(aliases):
    
    target_types = dict(aliases.target_types)
    for alias, factory in aliases.target_macro_factories.items():
      target_type, = factory.target_types
      target_types[alias] = target_type
    return target_types
docs: Given BuildFileAliases, return the concrete target types constructed for each alias.