How to use the scour.scour.SVGLength function in scour

def properlySizeDoc(docElement, options):
   # get doc width and height
   w = SVGLength(docElement.getAttribute('width'))
   h = SVGLength(docElement.getAttribute('height'))

   # if width/height are not unitless or px then it is not ok to rewrite them into a viewBox.
   # well, it may be OK for Web browsers and vector editors, but not for librsvg.
   if options.renderer_workaround:
      if ((w.units != Unit.NONE and w.units != Unit.PX) or
         (h.units != Unit.NONE and h.units != Unit.PX)):
          return

   # else we have a statically sized image and we should try to remedy that

   # parse viewBox attribute
   vbSep = re.split("\\s*\\,?\\s*", docElement.getAttribute('viewBox'), 3)
   # if we have a valid viewBox we need to check it
   vbWidth,vbHeight = 0,0
   if len(vbSep) == 4:

def properlySizeDoc(docElement, options):
   # get doc width and height
   w = SVGLength(docElement.getAttribute('width'))
   h = SVGLength(docElement.getAttribute('height'))

   # if width/height are not unitless or px then it is not ok to rewrite them into a viewBox.
   # well, it may be OK for Web browsers and vector editors, but not for librsvg.
   if options.renderer_workaround:
      if ((w.units != Unit.NONE and w.units != Unit.PX) or
         (h.units != Unit.NONE and h.units != Unit.PX)):
          return

   # else we have a statically sized image and we should try to remedy that

   # parse viewBox attribute
   vbSep = re.split("\\s*\\,?\\s*", docElement.getAttribute('viewBox'), 3)
   # if we have a valid viewBox we need to check it
   vbWidth,vbHeight = 0,0
   if len(vbSep) == 4:
      try:

if node.getAttribute('cy') != '':
      cy = SVGLength(node.getAttribute('cy'))
      if node.nodeName in ['circle', 'ellipse']:
         if cy.value == 0:
            node.removeAttribute('cy')
            num += 1
      elif node.nodeName == "radialGradient":
         if ( (cy.value == 50  and cy.units == Unit.PCT) or
              (cy.value == 0.5 and cy.units == Unit.NONE and not node.getAttribute('gradientUnits') == 'userSpaceOnUse') ):
            node.removeAttribute('cy')
            num += 1

   # r - radialGradient: 50% (r="0.5" usually equals "0.5px" which only equals "50%" if gradientUnits="objectBoundingBox")
   if node.getAttribute('r') != '':
      if node.nodeName == 'radialGradient':
         r = SVGLength(node.getAttribute('r'))
         if ( (r.value == 50  and r.units == Unit.PCT) or
              (r.value == 0.5 and r.units == Unit.NONE and not node.getAttribute('gradientUnits') == 'userSpaceOnUse') ):
            node.removeAttribute('r')
            num += 1

   # Summarily get rid of some more attributes
   attributes = [node.attributes.item(i).nodeName
              for i in range(node.attributes.length)]
   for attribute in attributes:
      if attribute not in tainted:
         if attribute in list(default_attributes.keys()):
            if node.getAttribute(attribute) == default_attributes[attribute]:
               node.removeAttribute(attribute)
               num += 1
            else:
               tainted = taint(tainted, attribute)

if node.getAttribute('x2') != '':
      x2 = SVGLength(node.getAttribute('x2'))
      if node.nodeName == 'line':
         if x2.value == 0:
           node.removeAttribute('x2')
           num += 1
      elif node.nodeName == 'linearGradient':
         if ( (x2.value == 100 and x2.units == Unit.PCT) or
              (x2.value == 1   and x2.units == Unit.NONE and not node.getAttribute('gradientUnits') == 'userSpaceOnUse') ):
            node.removeAttribute('x2')
            num += 1

   # y2 - line: 0
   #      linearGradient: 0%
   if node.getAttribute('y2') != '':
      y2 = SVGLength(node.getAttribute('y2'))
      if y2.value == 0:
         node.removeAttribute('y2')
         num += 1

   # fx: equal to rx
   if node.getAttribute('fx') != '':
      if node.getAttribute('fx') == node.getAttribute('cx'):
         node.removeAttribute('fx')
         num += 1

   # fy: equal to ry
   if node.getAttribute('fy') != '':
      if node.getAttribute('fy') == node.getAttribute('cy'):
         node.removeAttribute('fy')
         num += 1

def scourLength(length):
   """
   Scours a length. Accepts units.
   """
   length = SVGLength(length)

   return scourUnitlessLength(length.value) + Unit.str(length.units)

if node.getAttribute('cx') != '':
      cx = SVGLength(node.getAttribute('cx'))
      if node.nodeName in ['circle', 'ellipse']:
         if cx.value == 0:
            node.removeAttribute('cx')
            num += 1
      elif node.nodeName == "radialGradient":
         if ( (cx.value == 50  and cx.units == Unit.PCT) or
              (cx.value == 0.5 and cx.units == Unit.NONE and not node.getAttribute('gradientUnits') == 'userSpaceOnUse') ):
            node.removeAttribute('cx')
            num += 1

   # cy - circle / ellipse: 0
   #      radialGradient: 50% (cy="0.5" usually equals "0.5px" which only equals "50%" if gradientUnits="objectBoundingBox")
   if node.getAttribute('cy') != '':
      cy = SVGLength(node.getAttribute('cy'))
      if node.nodeName in ['circle', 'ellipse']:
         if cy.value == 0:
            node.removeAttribute('cy')
            num += 1
      elif node.nodeName == "radialGradient":
         if ( (cy.value == 50  and cy.units == Unit.PCT) or
              (cy.value == 0.5 and cy.units == Unit.NONE and not node.getAttribute('gradientUnits') == 'userSpaceOnUse') ):
            node.removeAttribute('cy')
            num += 1

   # r - radialGradient: 50% (r="0.5" usually equals "0.5px" which only equals "50%" if gradientUnits="objectBoundingBox")
   if node.getAttribute('r') != '':
      if node.nodeName == 'radialGradient':
         r = SVGLength(node.getAttribute('r'))
         if ( (r.value == 50  and r.units == Unit.PCT) or
              (r.value == 0.5 and r.units == Unit.NONE and not node.getAttribute('gradientUnits') == 'userSpaceOnUse') ):

def removeDuplicateGradientStops(doc):
   global numElemsRemoved
   num = 0

   for gradType in ['linearGradient', 'radialGradient']:
      for grad in doc.getElementsByTagName(gradType):
         stops = {}
         stopsToRemove = []
         for stop in grad.getElementsByTagName('stop'):
            # convert percentages into a floating point number
            offsetU = SVGLength(stop.getAttribute('offset'))
            if offsetU.units == Unit.PCT:
               offset = offsetU.value / 100.0
            elif offsetU.units == Unit.NONE:
               offset = offsetU.value
            else:
               offset = 0
            # set the stop offset value to the integer or floating point equivalent
            if int(offset) == offset: stop.setAttribute('offset', str(int(offset)))
            else: stop.setAttribute('offset', str(offset))

            color = stop.getAttribute('stop-color')
            opacity = stop.getAttribute('stop-opacity')
            style = stop.getAttribute('style')
            if offset in stops :
               oldStop = stops[offset]
               if oldStop[0] == color and oldStop[1] == opacity and oldStop[2] == style:

Also checks for the attributes actually being lengths, not 'inherit', 'none'
   or anything that isn't an SVGLength.

   Returns the number of bytes saved after performing these reductions.
   """
   num = 0

   styles = _getStyle(element)
   for lengthAttr in ['opacity', 'flood-opacity', 'fill-opacity',
                  'stroke-opacity', 'stop-opacity', 'stroke-miterlimit',
                  'stroke-dashoffset', 'letter-spacing', 'word-spacing',
                  'kerning', 'font-size-adjust', 'font-size',
                  'stroke-width']:
      val = element.getAttribute(lengthAttr)
      if val != '':
         valLen = SVGLength(val)
         if valLen.units != Unit.INVALID: # not an absolute/relative size or inherit, can be % though
            newVal = scourLength(val)
            if len(newVal) < len(val):
               num += len(val) - len(newVal)
               element.setAttribute(lengthAttr, newVal)
      # repeat for attributes hidden in styles
      if lengthAttr in list(styles.keys()):
         val = styles[lengthAttr]
         valLen = SVGLength(val)
         if valLen.units != Unit.INVALID:
            newVal = scourLength(val)
            if len(newVal) < len(val):
               num += len(val) - len(newVal)
               styles[lengthAttr] = newVal
   _setStyle(element, styles)