Provided by: systemtap-doc_2.3-1ubuntu1.4_all 

NAME
function::isdigit - Checks for a digit
SYNOPSIS
isdigit:long(str:string)
ARGUMENTS
str
string to check
DESCRIPTION
Checks for a digit (0 through 9) as the first character of a string. Returns non-zero if true, and a zero
if false.
SystemTap Tapset Reference March 2016 FUNCTION::ISDIGIT(3stap)