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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 add_pid(self, qname, sname, value, sym=True):
 """Add a percentage identity value to self.percentage_identity."""

        self.percentage_identity.loc[qname, sname] = value
        if sym:
            self.percentage_identity.loc[sname, qname] = value