'**SUMMARY**
Split the ROI at an x value.
x can be a list of sequentianl tuples of x 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**
* *x*-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.splitX(50) # create two ROIs'

def splitX(self, x, 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(x, (list, tuple))):
        x = [x]
    if unitVals:
        x = self.CoordTransformX(x, intype='ROI_UNIT', output='SRC')
    elif (not srcVals):
        x = self.CoordTransformX(x, intype='ROI', output='SRC')
    for xt in x:
        if ((xt < self.xtl) or (xt > (self.xtl + self.w))):
            logger.warning('Invalid    split    point.')
            return None
    x.insert(0, self.xtl)
    x.append((self.xtl + self.w))
    for i in xrange(0, (len(x) - 1)):
        xstart = x[i]
        xstop = x[(i + 1)]
        w = (xstop - xstart)
        retVal.append(ROI(xstart, self.ytl, w, self.h, self.image))
    return retVal
