code: def injectables_specs_for_key(self, key):
      
      mapping = self.injectables_spec_mapping
      if key not in mapping:
        raise self.NoMappingForKey(key)
      specs = mapping[key]
      assert isinstance(specs, list), (
        'invalid `injectables_spec_mapping` on {!r} for key "{}". '
        'expected a `list` but instead found a `{}`: {}'
      ).format(self, key, type(specs), specs)
      return [Address.parse(s).spec for s in specs]
docs: Given a key, yield all relevant injectable spec addresses.
  
      :API: public