ReqNum.neg constructor
Constrains data to negative numbers (zero excluded).
blank
the error message in case of a null or empty input value.
mal
"malformed", the error message in case of non-numeric input values.
pos
the error message if an input value is positive; the default value
is 'it cannot be positive'.
Implementation
ReqNum.neg({String? blank, String? mal, String? pos})
: this._num(Num.neg(mal: mal, pos: pos), blank);