Bosala expression regex oyo elongolaka maloba oyo ezali na letre "x".
 Expression regex oyo elandi ekoki kosalelama pona kolongolama maloba oyo ezali na letre "x" (insensibles na ba caches): ``` \b((?![Xx])[a-zA-Z])+\b ``` Oyo expression esalelaka lookahead ya mabe (?!) mpo na kolongolaka maloba oyo ezali na letre "x" to "X", mpe ndelo ya maloba `\b` esalaka ete ekokana kaka na maloba mobimba.