TO_UNSIGNED_LONG

Converts an input value to an unsigned long value.The input can be a single- or multi-valued field or an expression. The input
type must be of a boolean, date, string or numeric type.Example:
```esql
ROW str1 = "2147483648", str2 = "2147483648.2", str3 = "foo"
| EVAL long1 = TO_UNSIGNED_LONG(str1), long2 = TO_ULONG(str2), long3 = TO_UL(str3)
```

Note that in this example, the last conversion of the string isn’t
possible. When this happens, the result is a null value. In this case a
Warning header is added to the response. The header will provide information
on the source of the failure:"Line 1:133: evaluation of [TO_UL(str3)] failed, treating result as null. Only first 20 failures recorded."A following header will contain the failure reason and the offending value:"java.lang.NumberFormatException: Character f is neither a decimal digit number, decimal point, nor \"e\" notation exponential mark."If the input parameter is of a date type, its value will be interpreted as
milliseconds since the Unix epoch,
converted to unsigned long.Boolean true will be converted to unsigned long 1, false to 0.Alias: TO_ULONG, TO_UL