'**SUMMARY**
Split the ROI at an x value.
y can be a list of sequentianl tuples of y split points  e.g [0.3,0.6]
where we assume the top and bottom are also on the list.
Use units to split as a percentage (e.g. 30% down).
The srcVals means use coordinates of the original image.
**PARAMETERS**
* *y*-The split point. Can be a single point or a list of points. the type is determined by the flags.
* *unitVals* - Use unit vals for the split point. E.g. 0.5 means split at 50% of the ROI.
* *srcVals* - Use x values relative to the source image rather than relative to the ROI.
**RETURNS**
Returns a feature set of ROIs split from the source ROI.
**EXAMPLE**
>>> roi = ROI(0,0,100,100,img)
>>> splits = roi.splitY(50) # create two ROIs'

def splitY(self, y, unitVals=False, srcVals=False):

    retVal = FeatureSet()
    if (unitVals and srcVals):
        logger.warning('Not    sure    how    you    would    like    to    split    the    feature')
        return None
    if (not isinstance(y, (list, tuple))):
        y = [y]
    if unitVals:
        y = self.CoordTransformY(y, intype='ROI_UNIT', output='SRC')
    elif (not srcVals):
        y = self.CoordTransformY(y, intype='ROI', output='SRC')
    for yt in y:
        if ((yt < self.ytl) or (yt > (self.ytl + self.h))):
            logger.warning('Invalid    split    point.')
            return None
    y.insert(0, self.ytl)
    y.append((self.ytl + self.h))
    for i in xrange(0, (len(y) - 1)):
        ystart = y[i]
        ystop = y[(i + 1)]
        h = (ystop - ystart)
        retVal.append(ROI(self.xtl, ystart, self.w, h, self.image))
    return retVal
