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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 _parse_volumes(volume_values: dict) -> str: """Parse volumes key. Args: volume_values (dict):
 volume configuration values Returns: string, volume specification with mount source and container path """

        for v_values in volume_values:
            for v_key, v_value in v_values.items():
                if v_key == 'source':
                    if v_value == '.':
                        source = os.path.dirname(
                            os.path.abspath(__file__))
                    else:
                        source = v_value
                if v_key == 'target':
                    target = v_value
            volume_spec = [source + ':' + target]
            return volume_spec