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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 _BuildFindSpecsFromGroupName(self, group_name, environment_variables):
 """Builds find specifications from a artifact group name. Args: group_name (str):
 artifact group name. environment_variables (list[str]):
 environment variable attributes used to dynamically populate environment variables in file and registry artifacts. Returns: list[dfwinreg.FindSpec|dfvfs.FindSpec]: find specifications or None if no artifact with the given name can be retrieved. """

    definition = self._artifacts_registry.GetDefinitionByName(group_name)
    if not definition:
      return None

    return self._BuildFindSpecsFromArtifact(definition, environment_variables)