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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_by_name(self, name, style_type = None):
 """Find style by it's descriptive name. :Returns: Returns found style of type :class:`ooxml.doc.Style`. """

        for st in self.styles.values():
            if st:
                if st.name == name:
                    return st

        if style_type and not st:
            st = self.styles.get(self.default_styles[style_type], None)            
        return st