def get_voxel_spacing(hdr):
    """
    Extracts the voxel spacing from an image header.

    Notes
    -----
    It is recommended to call `hdr.get_voxel_spacing()` instead
    of this function.
    
    Parameters
    ----------
    hdr : medpy.io.Header
        An image header as returned by `load`.
    
    Returns
    -------
    pixel_spacing : tuple of floats
        The image's pixel spacing.
    """
    return hdr.get_voxel_spacing()
