def METHOD_NAME(self, attributes, requester, provider):
    syn_attributes = dict()
    context = dict()
    for attr_name, values in attributes.items():
        context[attr_name] = MustachAttrValue(
            attr_name,
            values
            if values
            and isinstance(values, list)
            and all(isinstance(value, str) for value in values)
            else [],
        )
    recipes = get_dict_defaults(self.synthetic_attributes, requester, provider)
    for attr_name, fmt in recipes.items():
        syn_attributes[attr_name] = [
            value
            for token in re.split("[;\n]+", render_mustache(fmt, context))
            for value in [token.strip().strip(';')]
            if value
        ]
    return syn_attributes