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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 get_short_plot_name(self, goobj):
 """Shorten some GO names so plots are smaller."""

        name = goobj.name
        if self._keep_this(name):
            return self.replace_greek(name)
        name = name.replace("cellular response to chemical stimulus",
                            "cellular rsp. to chemical stim.")
        depth = goobj.depth
        if depth > 1:
            name = name.replace("regulation of ", "reg. of ")
            name = name.replace("positive reg", "+reg")
            name = name.replace("negative reg", "-reg")
            name = name.replace("involved in", "in")
        if depth > 2:
            name = name.replace("antigen processing and presentation", "a.p.p")
            name = name.replace("MHC class I", "MHC-I")
            if depth == 4:
                if goobj.id == "GO:0002460":
                    before = " ".join([
                        "adaptive immune response based on somatic recombination of",
                        "immune receptors built from immunoglobulin superfamily domains"])
                    name = name.replace(
                        before,
                        "rsp. based on somatic recombination of Ig immune receptors")
            if depth > 3:
                name = name.replace("signaling pathway", "sig. pw.")
                name = name.replace("response", "rsp.")
                name = name.replace("immunoglobulin superfamily domains", "Ig domains")
                name = name.replace("immunoglobulin", "Ig")
            if depth > 4:
                name = name.replace("production", "prod.")
            if depth == 6 or depth == 5:
                name = name.replace("tumor necrosis factor", "TNF")
        name = self.replace_greek(name)
        return name