xid

Package xid implements validation functions for unicode identifiers,
as defined in UAX#31: https://unicode.org/reports/tr31/.
The syntax for an identifier is:

<identifier> := <xid_start> <xid_continue>*

where <xid_start> and <xid_continue> derive from <id_start> and
<id_continue>, respectively, and check their NFKC normalized forms.