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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def target_types_from_build_file_aliases(aliases):
 """Given BuildFileAliases, return the concrete target types constructed for each alias."""

  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