def draw_graph_paper(width, height)
      background color: 'white'
      grid width: 50,  height: 50,  stroke_color: '#659ae9', stroke_width: 1.5
      grid width: 200, height: 200, stroke_color: '#659ae9', stroke_width: 3, x: 50, y: 50
      (50..height).step(200) do |y|
        text str: "y=#{y}", x: 3, y: y - 18, font: 'Open Sans, Sans 10'
      end
    end
def draw_graph_paper(width, height)
      background color: 'white'
      grid width: 50,  height: 50,  stroke_color: '#659ae9', stroke_width: 1.5
      grid width: 200, height: 200, stroke_color: '#659ae9', stroke_width: 3, x: 50, y: 50
      (50..height).step(200) do |y|
        text str: "y=#{y}", x: 3, y: y - 18, font: 'Open Sans, Sans 10'
      end
    end
Draw graph paper for samples