def check_ascending(ra, dec, vel, verbose=False):
    """
    Check if the RA, DEC and VELO axes of a cube are in ascending order.
    It returns a step for every axes which will make it go in ascending order.
    
    :param ra: RA axis.
    :param dec: DEC axis.
    :param vel: Velocity axis.
    :returns: Step for RA, DEC and velocity.
    :rtype: int,int,int
    """
    
    if vel[0] > vel[1]: 
        vs = -1
        if verbose:
            print("Velocity axis is inverted.")
    else:
        vs = 1
            
    if ra[0] > ra[1]:
        rs = -1
        if verbose:
            print("RA axis is inverted.")
    else:
        rs = 1
        
    if dec[0] > dec[1]:
        ds = -1
        if verbose:
            print("DEC axis is inverted.")
    else:
        ds = 1
        
    return rs, ds, vs