def METHOD_NAME(cls):
    """Get the global FSL output file type FSLOUTPUTTYPE.
    This returns the value of the environment variable
    FSLOUTPUTTYPE.  An exception is raised if it is not defined.
    Returns
    -------
    fsl_ftype : string
        Represents the current environment setting of FSLOUTPUTTYPE
    """
    try:
        return os.environ["FSLOUTPUTTYPE"]
    except KeyError:
        IFLOGGER.warning(
            "FSLOUTPUTTYPE environment variable is not set. "
            "Setting FSLOUTPUTTYPE=NIFTI"
        )
        return "NIFTI"