def osr_proj(input_osr):
    """Return the projection WKT of a spatial reference object

    Parameters
    ----------
    input_osr : class:`osr.SpatialReference`
        The input OSR spatial reference.

    Returns
    -------
    WKT: :class:`osr.SpatialReference` in WKT format

    """
    return input_osr.ExportToWkt()
