def AddValue(self, registry_value):
name = registry_value.name.upper()<EOL>if name in self._values:<EOL><INDENT>raise KeyError(<EOL>'<STR_LIT>'.format(registry_value.name))<EOL><DEDENT>self._values[name] = registry_value<EOL>
Adds a value.

        Args:
          registry_value (WinRegistryValue): Windows Registry value.

        Raises:
          KeyError: if the value already exists.