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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fill_stroke(self, fill = None, stroke = None, opacity = 1, line_width = None):
 """fill and stroke the drawn area in one go"""

        if line_width: self.set_line_style(line_width)

        if fill and stroke:
            self.fill_preserve(fill, opacity)
        elif fill:
            self.fill(fill, opacity)

        if stroke:
            self.stroke(stroke)