def key_plain
import bend-toon-codec@0.1.0.0/src/text.bend as Textimport Base
144# `^[A-Za-z_][A-Za-z0-9_.]*$`.
145def key_plain(+s: String) -> Bool:
146 match s:
147 case SNil{}:
148 False{}
149 case SCon{c, t}:
150 key_start(c) && key_tail(t)