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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 merge(self, parent=None):
 """ Merge parent data """

        # Check parent, append source files
        if parent is None:
            parent = self.parent
        if parent is None:
            return
        self.sources = parent.sources + self.sources
        # Merge child data with parent data
        data = copy.deepcopy(parent.data)
        for key, value in sorted(self.data.items()):
            # Handle attribute adding
            if key.endswith('+'):
                key = key.rstrip('+')
                if key in data:
                    # Use dict.update() for merging dictionaries
                    if type(data[key]) == type(value) == dict:
                        data[key].update(value)
                        continue
                    try:
                        value = data[key] + value
                    except TypeError as error:
                        raise utils.MergeError(
                            "MergeError: Key '{0}' in {1} ({2}).".format(
                                key, self.name, str(error)))
            # And finally update the value
            data[key] = value
        self.data = data