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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 metadata2properties(self, field):
 """Return a dictionary of properties extracted from field Metadata Will include field metadata that are valid properties of `OpenAPI schema objects <https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#schemaObject>`_ (e.g. “description”, “enum”, “example”). In addition, `specification extensions <https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#specification-extensions>`_ are supported. Prefix `x_` to the desired extension when passing the keyword argument to the field constructor. apispec will convert `x_` to `x-` to comply with OpenAPI. :param Field field: A marshmallow field. :rtype: dict """

        # Dasherize metadata that starts with x_
        metadata = {
            key.replace("_", "-") if key.startswith("x_") else key: value
            for key, value in iteritems(field.metadata)
        }

        # Avoid validation error with "Additional properties not allowed"
        ret = {
            key: value
            for key, value in metadata.items()
            if key in _VALID_PROPERTIES or key.startswith(_VALID_PREFIX)
        }
        return ret