How to use the 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 not options.override_size:
	  # 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 not options.override_size:
	  # 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

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 stops.has_key(offset) :
					oldStop = stops[offset]
					if oldStop[0] == color and oldStop[1] == opacity and oldStop[2] == style:

'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 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)
	
	for child in element.childNodes:
		if child.nodeType == 1:
			num += reducePrecision(child)
	
	return num

del styleMap[uselessFillStyle]
						num += 1
		
		#  stroke-opacity: 0
		if styleMap.has_key('stroke-opacity') :
			strokeOpacity = float(styleMap['stroke-opacity']) 
			if strokeOpacity == 0.0 :
				for uselessStrokeStyle in [ 'stroke', 'stroke-width', 'stroke-linejoin', 'stroke-linecap', 
							'stroke-dasharray', 'stroke-dashoffset' ] :
					if styleMap.has_key(uselessStrokeStyle): 
						del styleMap[uselessStrokeStyle]
						num += 1

		# stroke-width: 0
		if styleMap.has_key('stroke-width') :
			strokeWidth = SVGLength(styleMap['stroke-width']) 
			if strokeWidth.value == 0.0 :
				for uselessStrokeStyle in [ 'stroke', 'stroke-linejoin', 'stroke-linecap', 
							'stroke-dasharray', 'stroke-dashoffset', 'stroke-opacity' ] :
					if styleMap.has_key(uselessStrokeStyle): 
						del styleMap[uselessStrokeStyle]
						num += 1
		
		# remove font properties for non-text elements
		# I've actually observed this in real SVG content
		if not mayContainTextNodes(node):
			for fontstyle in [ 'font-family', 'font-size', 'font-stretch', 'font-size-adjust', 
								'font-style', 'font-variant', 'font-weight', 
								'letter-spacing', 'line-height', 'kerning',
								'text-align', 'text-anchor', 'text-decoration',
								'text-rendering', 'unicode-bidi',
								'word-spacing', 'writing-mode'] :

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 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)

num = 0
	if node.nodeType != 1: return 0
	
	# gradientUnits: objectBoundingBox
	if node.getAttribute('gradientUnits') == 'objectBoundingBox':
		node.removeAttribute('gradientUnits')
		num += 1
		
	# spreadMethod: pad
	if node.getAttribute('spreadMethod') == 'pad':
		node.removeAttribute('spreadMethod')
		num += 1
		
	# x1: 0%
	if node.getAttribute('x1') != '':
		x1 = SVGLength(node.getAttribute('x1'))
		if x1.value == 0:
			node.removeAttribute('x1')
			num += 1

	# y1: 0%
	if node.getAttribute('y1') != '':
		y1 = SVGLength(node.getAttribute('y1'))
		if y1.value == 0:
			node.removeAttribute('y1')
			num += 1

	# x2: 100%
	if node.getAttribute('x2') != '':
		x2 = SVGLength(node.getAttribute('x2'))
		if (x2.value == 100 and x2.units == Unit.PCT) or (x2.value == 1 and x2.units == Unit.NONE):
			node.removeAttribute('x2')

if node.getAttribute('cx') != '':
		cx = SVGLength(node.getAttribute('cx'))
		if (cx.value == 50 and cx.units == Unit.PCT) or (cx.value == 0.5 and cx.units == Unit.NONE):
			node.removeAttribute('cx')
			num += 1

	# cy: 50%
	if node.getAttribute('cy') != '':
		cy = SVGLength(node.getAttribute('cy'))
		if (cy.value == 50 and cy.units == Unit.PCT) or (cy.value == 0.5 and cy.units == Unit.NONE):
			node.removeAttribute('cy')
			num += 1

	# r: 50%
	if node.getAttribute('r') != '':
		r = SVGLength(node.getAttribute('r'))
		if (r.value == 50 and r.units == Unit.PCT) or (r.value == 0.5 and r.units == Unit.NONE):
			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 default_attributes.keys():
				if node.getAttribute(attribute) == default_attributes[attribute]:
					node.removeAttribute(attribute)
					num += 1
				else:
					tainted = taint(tainted, attribute)
	# These attributes might also occur as styles

if node.getAttribute('y1') != '':
		y1 = SVGLength(node.getAttribute('y1'))
		if y1.value == 0:
			node.removeAttribute('y1')
			num += 1

	# x2: 100%
	if node.getAttribute('x2') != '':
		x2 = SVGLength(node.getAttribute('x2'))
		if (x2.value == 100 and x2.units == Unit.PCT) or (x2.value == 1 and x2.units == Unit.NONE):
			node.removeAttribute('x2')
			num += 1

	# y2: 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