def parse(node)
      node.xpath('*').each do |math_run_child|
        case math_run_child.name
        when 'rPr'
          @properties = MathRunProperties.new(parent: self).parse(math_run_child)
        when 't'
          @text = math_run_child.text
        end
      end
      self
    end
def parse(node)
      node.xpath('*').each do |math_run_child|
        case math_run_child.name
        when 'rPr'
          @properties = MathRunProperties.new(parent: self).parse(math_run_child)
        when 't'
          @text = math_run_child.text
        end
      end
      self
    end
Parse MathRun
 @param [Nokogiri::XML:Node] node with MathRun
 @return [MathRun] result of parsing