A fastener having two branches extending on either side of a median plane, each branch carrying a tongue, the tongues defining between them a throat between the two branches. When the fastener is reversed with respect to another identical fastener, their respective median planes forming a non-zero angle between them, one branch of the fastener having its distal portion in contact with at least one of the two tongues of the other fastener and its outer face in contact with an inner face of one branch of the other fastener, the distal portion of the other branch of the fastener is substantially in contact with the distal portion of the other branch of the other fastener.