backslashit()

backslashit( string $value ): string

function backslashit( $value ) {
	if ( isset( $value[0] ) && $value[0] >= '0' && $value[0] <= '9' ) {
		$value = '\\\\' . $value;
	}
	return addcslashes( $value, 'A..Za..z' );
}