def METHOD_NAME(ssl_context):
    """
    Raises a ProxySchemeUnsupported if the provided ssl_context can't be used
    for TLS in TLS.
    The only requirement is that the ssl_context provides the 'wrap_bio'
    methods.
    """
    if not hasattr(ssl_context, "wrap_bio"):
        if six.PY2:
            raise ProxySchemeUnsupported(
                "TLS in TLS requires SSLContext.wrap_bio() which isn't "
                "supported on Python 2"
            )
        else:
            raise ProxySchemeUnsupported(
                "TLS in TLS requires SSLContext.wrap_bio() which isn't "
                "available on non-native SSLContext"
            )