Matches any single letter (A-Z, a-z) or digit (0-9).
xp_build_alnum(pattern = NULL)A regexpert object.
# Match a string of 8 alphanumeric characters (like a serial number)
xp_build_alnum() %>% xp_op_repeat(8)
#> <regexpert pattern>
#> (?:[A-Za-z0-9]){8}